Thin Films - Science topic

Dear Ricardo Tadeu Maia,

Thank you for your suggestions.

We usually use ITO as our substrate, but for this instance, we need something that is non-conductive, so we are trying deposition on microscope slides made from soda-lime glass. Regarding the cleaning process for soda-lime glass, we’ve found that it is quite rare in literature, but in one paper, we saw that they employed a cleaning process similar to the one for ITO, except that they did not use the UV-ozone cleaner at the end, which is typically part of our usual cleaning protocol for ITO.

For the spin-coating, we will try adjusting the conditions and explore different variations. We are also using static deposition. While we usually employ a two-step annealing method, we are considering testing a one-step annealing process at lower temperatures to see if it offers better results. Additionally, we had thought about filtering the precursor, although we haven't tried it yet; we plan to experiment with it now.

Ricardo Tadeu Maia Ricardo Tadeu Maia

Our main issue so far has been that the FAPbI3 solution doesn’t seem to adhere well to the soda-lime glass if we skip the UV Ozone cleaning step. Even when we use the UV-ozone cleaner, we’ve observed that the FAPbI3 film degrades a couple of hours after deposition.

Thank you again for your helpful suggestions, and we will definitely keep them in mind as we continue our work.

Best regards, Barbara.

I think this is due to the non-adjustable metal/chalcogen ratio. During the reaction with selenium powder, compositional inhomogeneities are possible. Many transition metals exhibit different valences. Therefore, the local composition may be different. And at different valences, materials have different crystal structures and, therefore, volumes. Hence the inhomogeneities in the morphology of your film.

As for me, it is better to selenize using selenium vapor. This will be much more homogeneous due to the much greater diffusion mobility of selenium in the vapor than in the solid state.

Dear Jojo,

The sheet resistance of thin layers of Ti cannot be calculated by using the bulk value of Ti resistivity. For thin films, especially yours of 23 nm, the resistance is determined for the major part by the way you have deposited the Ti. For this you should look up Thornton's model for vapor deposition. It shows how morphology of thin layers is changed by process parameters like material melting temperature, actual surface temperature during processing and process pressure. Depending on these parameters you will get polycrystalline, microcrystalline, transition (T) structure of fibrous grains or columnar pillar growth. The average free electron path in metals is ca. 50 nm. If you go below this value in layer thickness, morphology of the film has a tremendous impact on resistivity. So you have to characterize the resistivity at this thickness of 23 nm in terms of the process settings.

Cleaning the substrate thoroughly... Like sonicating with acetone... Then etching with strong acids like HCl or even with aqua regia... Then washing several times with DI water

If possible plasma clean it... (Best way)

If u are doing thin film... It's not straightforward...

After deposition when your thinfilm is ready... U can scratch out the film ...then disperse in solvent like water or ethanol... Sonicate it... Provided ur materials doesn't disolve in the solvent... Then drop it on copper grid....

1) Since u haven't doped try annealing around 450-550 °C for 2-4 hrs. Annealing comes with risk... If u r expecting crystalite size to be <150nm annealing at 550 °C is not a good choice...

2) if u see ur XRD; at lower angles <20°if u see a hump it will tell it's still amorphous phase

Ref:

Gerhard Martens Thank you very much for the answer!

Soak the glass slides in pirana solution for 10 min then clean with isopropyl alcohol, acetone finally with DI water. This can improve the film adhesion

Thank you, Dr

You can use DNP 10 or DNP S10 Bruker. Use a higher spring constant (e.g. 0.35 N/m or 0.24 N/m).

There are 3 options to measure the thickness.

1. scratch the film using cantilever (e.g. 2x2 micrometer). Use contact mode, set deflection setpoint to high value (e.g. >6 V) and scan rate to high value (4 Hz). scan it 10 times and zoom out, then check the profile.

2. Make a force-distance curve. If you find the breaktrough point, that is the thickness of the film.

3. or you can scratch the film using a knife and check with AFM. measure the profile later on.

Definitely, you should use contact mode.

Hi,

I'm recently working on the EIS test on my gold IDEs (2.5 um width and 1.5 um spacing, coated with 5 nm PEG) using the 2-electrodes method. Regarding the AC amplitude, I used ~80 mV, and I observed the hydrolysis (gas bubbles came out from the electrodes). I'm very new to this experiment, so any suggestion from you will be appreciated!

The necessity of Omega (Ω), Chi (Ψ), and Phi (Φ) scans in grazing incidence X-ray diffraction (GIXRD) for thin films lies in their ability to provide comprehensive information about the crystalline properties of the film:

Thank you very much Prof. Gerhard Martens

Nickel-doped ZnO (Ni:ZnO) materials, whether in powder or thin film form, have a variety of applications due to their unique properties.

Kindly go through some literature for further clarity.

Main question:

If you look at the basic structures fcc and hcp, you find that fcc(111) and hcp(001) are both maximum density packed surface structures with triangles. Therefore these two facets match with each other and you can do epitaxy there. Please be aware that, since fcc has an abcabc stacking and hcp just ababab, an fcc-derived layer provides one additional "structure variable" about the stacking direction, so you can expect epitaxial growth without any texture issues of hcp(001) on fcc(111), but if you try it the other way round, you can expect the fcc layer to stack both abcabc and cbacba (symmetry-equivalent to a 60° or 180° rotated domain), so if you check the texture with an XRD pole figure, you can expect twice as many spots as on a single crystal.

Secondary question:

The adatoms can be bound to the substrate by any known kind of bond, be it van der Waals, covalent, ionic, metallic or quite often a mix of them. That's not a question of the crystal structure but more a question of what the specifice atoms prefer when they react with each other.

If you want to get quantum yield, you can do it by two methods. The first is comparative, which means that you have some standard with a known quantum yield, e.g. Phthalocyanine has 0.6 (Seybold, 1969a). You then measure the emission and absorption spectrum of the sample as well as the standard at different concentrations. You integrate the fluorescence bands and then plot a graph of the integrated fluorescence intensity vs absorbance. The quantum yield of the unknown sample is given by the equation:

Q_s = Q_r x (a_s/a_r) x (n_s/n_r)^2

Where: Q - quantum yield

a - slope of the graph

n - refractive index

subscripts s (sample) and r (reference)

The second method is a direct measurement using an integrating sphere. Then you know the ratio of photons emitted to photons absorbed. the case of your film measurements, it seems to me that this would be a better method

As for the aggregated environment, you already get some confirmation from the spectra you uploaded. The band at about 465 nm in the film comes from aggregated molecules

Its not an answer on my question.

hello did you find any solution? please inform us if do

I think I figured out the issue. The peaks in fluorimeter are probably artifacts. While Raman started showing shifts in peak position after treatment, the fluorimeter peak didn’t show any change in position.

To create adherent polyaniline thin films on glass, prepare a well-dissolved aqueous solution of aniline with a strong acid, and clean the glass substrate thoroughly. Use deposition methods like spin or electrochemical coating, and consider doping and curing to enhance film quality and adhesion.

Hello, you can solve this error by specifying that the surface is thin (yes) through the options at the bottom left, located below the program's workbench. In addition, you can specify the thickness of this thin surface through the options in the same place.

İletken metal doplayarak veya yüksek enerjili foton depolayarak iletkenliği arttırılabilir.

Hi Rodriguez,

UW LASER is engaged in laser-scriber for the photovoltaic industry.

Due to geometric factors from beam profile, beam size, and sample size, microscopic samples have dramatically changed X-ray reflectivity (XRR) profiles. Geometric factors raise the spill-over angle, which sometimes surpasses the critical angle for small samples. To separate geometric components, know the spill-over angle. The XRR profile of microscopic samples cannot determine the spill-over angle because geometric characteristics smoothly vary and extend beyond the crucial angle. Comparing the normal X-ray reflectivity (XRR) profile of a tiny sample to a surface-contact knife edge profile on the same sample may estimate the spill-over angle. A technique has been developed to compress tiny sample data and verify it using testing. Unlike limited techniques, this data reduction strategy is self-consistent.@Sean Clark

The ISHE signal is dependent on the type of interface you have and is caracterized by the geff factor which is the spin mixing conductance. Thus you want a surface with little defects as possible.

For rough surfaces you also have the two magnon scattering process which increases the linewidth (dH) making the ISHE voltage/current to be small as it is proporcional to (1/dH)^2. Note that when caracterizing YIG one looks to the Landau alfa parameter but when talking about ISHE one should looks at the linewidht itself.

In your case it seens too me you just have a large dH and are not using enough rf power to see the signal.

PS: W and Ta have negative Hall angle, thus for your referance frame the ISHE voltage of those materials should be opposite to Pt,Pd or Au.

thank you guys for your answer, but now I change the gelatin with gliserol and facing the same problem

Look at articles by Scott Prahl (Oregon Medical Laser Center) on a technique called Inverse Adding Doubling. For example:

Some nice software at:

If I were you I would like to try light profilometry.

Enhancing the wettability and adhesion of fluorosilanes on various surfaces can be challenging due to their low surface energy and hydrophobic nature. However, there are several strategies you can employ to improve their performance:

1. Surface Pretreatment

Proper surface preparation is crucial for improving the adhesion of fluorosilanes.

2. Primer Application

Using a suitable primer can significantly improve the adhesion of fluorosilanes.

3. Optimizing Fluorosilane Concentration and Application

Adjusting the concentration and method of application can influence the performance of fluorosilanes.

4. Thermal Treatment

Thermal curing or annealing can enhance the bonding and cross-linking of fluorosilanes.

5. Mixing with Other Functional Groups

Incorporating other functional groups can improve the adhesion properties of fluorosilanes.

6. Environmental Considerations

Ensure optimal environmental conditions during application.

Summary

By following these strategies, you can significantly enhance the wettability and adhesion of fluorosilanes on various surfaces.

4o

Use a mortar and pestle or a dedicated grinding machine to ensure fine grinding without clumping, achieving an even distribution of the sample.

Adding a small amount of ethanol or acetone during grinding can prevent clumping and improve sample dispersion. After grinding, thoroughly mix the powder to achieve uniform distribution and avoid uneven packing or clumps.

Spread the powder thinly and evenly on the sample holder, using techniques like light tapping to ensure uniform distribution.

Precisely align the sample and adjust detector parameters to balance density across various scattering angles.

Effectively use a zero-background silicon holder and select appropriate background fitting regions to isolate the sample scattering pattern from background noise. Refine peak shape, broadening, and other parameters accurately in Rietveld analysis.

Ensure peak integration settings are optimized for accurate measurement and integration of all peaks. Use integrated peak intensities as inputs for Rietveld analysis.

Experiment with different grinding techniques or alternative sample forms ,for examples (pellets, compressed powders) to improve sample flow and reduce clumping.

Dear Aakash Mathew ,

in addiiton to the answer of Thomas Walther

I want to add that the attenuation coefficents (x-ray mass-attenuation coefficients (µ/rho)) can be taken from the NIST/XCOM data base.

https://physics.nist.gov/PhysRefData/Xcom/html/xcom1.html

I understand, we coat a film and then check the quality of the film using MB. after removal of MB, we didn't see any negative effect on the film. but of course, application and synthesis parameters may vary.

Hello

We are in France. We usually make ECV profiling on silicon and III-V semiconductors. We would be very pleased to do measurements on your samples.

Best regards.

Bernard Sermage

Atomic-scale defects can significantly influence the electronic and optical properties of thin films in emerging semiconductor materials. The potential effects include:

1. Altered Electronic Properties: Defects such as vacancies, interstitials, and antisite defects can modify the electronic band structure, potentially creating new energy levels within the bandgap. This can affect the material's conductivity and carrier mobility.

2. Impact on Optical Properties: Defects can lead to changes in absorption, reflection, and transmission spectra. For example, they can introduce localized states that absorb specific wavelengths, thus altering the material's optical response.

3. Influence on Photoluminescence: The presence of defects can quench or enhance photoluminescence, depending on their nature and density. This effect is crucial for optoelectronic applications such as light-emitting diodes and lasers.

4. Modulation of Charge Transport: Defects can act as traps for charge carriers, thereby reducing carrier lifetime and mobility. This can significantly impact the efficiency of devices like solar cells and transistors.

5. Changes in Refractive Index: Atomic-scale defects can alter the refractive index of thin films, affecting their use in applications requiring precise optical properties, such as in waveguides and photonic devices.

Overall, managing defects is crucial for optimizing the performance of semiconductor thin films in various electronic and optoelectronic applications.

Farah Qahtan In my case I only have the energy of spectral lines and their intensities. Primary intensity I0 is unknown. And also here the CuKα is not a spectral line but primary radiation. Is it possible to calculate the linear absorption coefficient by comparing the energy of the spectral lines and the primary radiation with the NIST database?

Integrating thin film technologies into existing wastewater treatment infrastructure offers a versatile approach to enhancing performance without requiring extensive modifications. These technologies, such as thin film composite membranes for filtration, coatings to improve membrane efficiency and longevity, and sensors for real-time monitoring, optimize treatment processes effectively. Photocatalytic thin films like titanium dioxide enable advanced oxidation processes, while energy harvesting films supplement power needs sustainably. Modular and smart grid integration further facilitate seamless adoption, allowing facilities to improve efficiency and sustainability without major disruptions.

These questions are excellent, and it's something everyone working on spintronics with vdW magnets considers. We've questioned ourselves on the advantages that vdW magnets can bring as well. Currently, it's challenging to provide a definitive answer because while vdW magnets offer numerous opportunities for spintronics, concrete beneficial examples are still emerging. Here's my perspective:

At present, it's more practical to appreciate the broad opportunities vdW magnets offer for advancing spintronics, generating new ideas, concepts, and physics that accelerate the field's development.

These points are my shallow understandings.

Timothy Imanobe Oliomogbe

Thin films belong to 2D nanostructures. Nanostructures have a large specific surface area that comes into contact with water. The larger the specific surface area, the greater the adsorption of pollutant molecules on it. In addition, of course, the adsorption properties of films and their durability depend on the synthesis method. There is no theory to predict these properties and therefore an experiment related to the chemical nature of the film and the synthesis method is necessary.

Hi Arpan,

In my opinion spin coating can give a better and easier to have a uniform coating thickness that can effect the photocatalytic activity. However you need to consider the medium used and the density of the catalyst that used. Good smooth surface also can be produced if using for coating application.

To achieve better photocatalytic activity in thin films, several parameters can be tuned and optimized. These parameters include material properties, fabrication methods, structural parameters, operational conditions, and additional enhancements. Material properties like composition, doping, crystal structure, morphology, surface area, bandgap engineering, and defects or vacancies are critical for optimizing electronic properties and enhancing activity. Fabrication methods such as chemical vapor deposition (CVD), physical vapor deposition (PVD), sol-gel, sputtering, and electrochemical deposition influence film thickness and uniformity. Annealing conditions and substrate types also affect crystallinity, phase composition, and film adhesion. Structural parameters like film thickness, porosity, and roughness are important for balancing light absorption, charge carrier transport, and reaction kinetics. Operational conditions, including light intensity and wavelength, reaction environment, reactant concentration, and flow rate, play a significant role in optimizing photocatalytic reactions. Additional enhancements like adding co-catalysts (e.g., Pt, Au, Ag), surface modifications, and designing multilayer structures with different materials can further improve charge separation, selectivity, and overall activity. By carefully tuning these parameters, the photocatalytic activity of thin films can be significantly improved for applications such as environmental remediation, water splitting, and solar energy conversion.

Yes, the methods of calculating the absorption coefficient (α) from absorbance can differ between powder samples and thin films due to differences in their physical properties and how light interacts with these materials.

Absorption Coefficient (α) Calculation

General Formula

The absorption coefficient (α) can be calculated using the Beer-Lambert law:

A=α⋅d

where:

• A is the absorbance (dimensionless),

• α is the absorption coefficient (cm−1),

• d is the thickness of the sample (cm).

From this, the absorption coefficient can be derived as:

α=A/d

Thin Films:

For thin films, the calculation is more straightforward because the sample thickness is usually well-defined and uniform.

Key Considerations for Thin Films:

1. Thickness (d): Precise measurement of film thickness is crucial. Techniques such as ellipsometry or profilometry are often used to measure thickness.

2. Optical Interferences: Thin films can exhibit interference effects due to multiple reflections within the film. These effects can create oscillations in the absorption spectrum. Careful analysis is needed to account for these interferences.

3. Refractive Index: The refractive index of the film and the substrate can influence the absorption measurements. Knowing these indices helps in correcting for reflection losses.

4. Uniformity: Ensuring the film is uniform across the sample area to avoid variations in the absorbance measurements.

Powders:

For powder samples, the situation is more complex because powders do not have a well-defined thickness and light scattering plays a significant role.

Key Considerations for Powders:

1. Effective Path Length (d): The effective path length in a powder sample is less well-defined than in thin films. It can be estimated using the packing density and the sample thickness, but it's an approximation.

2. Scattering: Powders scatter light, which complicates the direct application of Beer-Lambert law. Scattering needs to be accounted for, often by using integrating spheres to measure diffuse reflectance and transmittance.

3. Sample Preparation: The sample's homogeneity and packing density can influence absorbance measurements. Ensuring consistent sample preparation is essential.

4. Kubelka-Munk Theory: This theory is often used to analyze the absorption of powders. It relates the reflectance and absorption coefficients, accounting for scattering:

K=αS

α= (1−R)^2/2R

where:

• K is the absorption coefficient,

• S is the scattering coefficient, and

• R is the reflectance.

Techniques for Each Sample Type

Thin Films:

• Spectrophotometry: Direct measurement of transmittance and reflectance.

• Ellipsometry: Provides thickness and optical constants.

• Interference Correction: Analytical or numerical methods to account for interference effects.

Powders:

• Integrating Sphere: Measures total transmittance and reflectance, reducing the impact of scattering.

• Diffuse Reflectance Spectroscopy (DRS): Analyzes the reflected light from powders to determine absorption and scattering.

• Kubelka-Munk Analysis: Converts reflectance data to absorption coefficients.

Practical Steps for Calculation:

Thin Films:

1. Measure the absorbance spectrum using a spectrophotometer.

2. Measure the film thickness using an appropriate technique.

3. Correct for any interference effects.

4. Calculate the absorption coefficient using the modified Beer-Lambert law.

Powders:

1. Prepare a homogeneous powder sample.

2. Measure diffuse reflectance using an integrating sphere.

3. Apply the Kubelka-Munk theory to convert reflectance data to absorption coefficient.

4. Account for scattering and packing density effects.

By considering these factors and employing appropriate techniques, accurate determination of the absorption coefficient (α) can be achieved for both thin films and powder samples.

TLC is one of the best analytical techniques used for separating mixed components some times by our naked eye or by using ultraviolet lamp under short wave length and long wave length. We use tlc as stationary phase where the solvents used for separation is mobile phase. For organic compounds extracted from natural products one scholar can use the tlc for checking crude extracts component before column and pure bioactive isolated compound after column or preparative thin layer chromatography. Generally, thin-layer chromatography (TLC) is a technique commonly used to separate and analyze mixtures of compounds. The Rf (retention factor) value is a crucial parameter in TLC analysis. It's calculated as the ratio of the distance traveled by the compound (spot) to the distance traveled by the solvent front. Here's how you can compare Rf values to known standards or literature values to identify compounds:

By comparing Rf values to known standards or literature values, you can tentatively identify compounds in your mixture based on their migration behavior in the TLC system. However, it's important to remember that factors such as the type of stationary phase, solvent system, and experimental conditions can influence Rf values, so thorough analysis and confirmation are essential.

Dear Rob,

Thank you for your advice, I will optimize accordingly and update.

Kind regards,

The term "displacement" implies that something has been moved from its rightful place, which gives it a negative connotation. In contrast, "shift" is emotionally neutral. Additionally, I feel like the "displacement" typically refers to physical objects.

In any case, you shouldn't be concerned about repetition. Scientific papers aren't poetry, and repetition can actually enhance clarity and comprehension.

One option might be sedimentation through slow evaporation of the dispersing solvent. Another might be through Langmuir film methods. A search shows the latter method has been published and also yields at least two patents for methods to deposit tungsten oxide coatings on glass.

Thank you so much Arpan Das for your answer.

Now, out of the ideal world, every thin film material optical properties depend on the deposition method and underlying materials. For example: in ITO, the ratio of oxide, tin and indium has a profile that depend on deposition method. Also, in certain cases, a "combined" dielectric function does exist (effective dielectric function), but this depends, among others, on the sample characteristics and the wavelength regime (dielectric "constants" are not constants, they are wavelength dependent).

Saying the above, as a first step, you can use material's dielectric functions from the literature and simulate the system response.

How to model the system? it depends on what do you want to model.

How to measure the dielectric functions? It depends on the sample characteristics and wavelength regime (dielectric "constants" are not constants, they are wavelength dependent). Ellipsometry is usually the best way to go.

See the following article on the determination of dielectric functions/optical constants on a stack system, as well as the modeling of the combined system:

With such a large thickness it could be the case that the metal film is very rough.

In this case it could lose its mirror-like appearance. The issue could be if you need a really flat surface, but for a thermocompression it's unlikely a requirement.

Dergham Driss See: https://www.researchgate.net/post/How_can_I_calculate_the_Absorption_coefficient_from_Absorbance2

and especially the contributions from @Thomas Mayerhöfer

Go through following articles:

1 )

2)

3)

Roberto D'Agosta many thanks i added k points mesh with 10 10 1 as your suggestion (have a mesh in the Brillouin Zone that has only one point in the z direction)

I think that the gas pressure is a critical factor. Increasing the gas pressure will raise the collision frequency and the sputtering rate, but it will reduce the average mean free path of the sputtered atoms to reach the substrate and will also reduce the adhesion.

So, it is better to control the gas pressure in low range to have better adhesion and allow a longer mean free path of the sputtered atoms reaching the substrate.

For this, please refer to the preprint article link http://dx.doi.org/10.13140/RG.2.2.23849.40808, titled “Determining and quantifying chemically produced stresses in (atoms of) electronic and crystalline materials”

For this, please refer to the preprint article link http://dx.doi.org/10.13140/RG.2.2.23849.40808, titled “Determining and quantifying chemically produced stresses in (atoms of) electronic and crystalline materials”

Konsantrasyon kırıcılık indisi ile doğru orantılı.

Hey there Nadir Fadhil Habubi! Great question. When the crystallite size estimated by XRD matches the grain size for thin films, it typically means that the XRD analysis is indeed capturing the grain size accurately. In thin films, XRD can provide valuable insights into both the crystal structure and the size of the crystallites or grains within the film. When these two measurements align, it suggests that the XRD technique is effectively probing the structure of the thin film, including the grain size. So, to answer your Nadir Fadhil Habubi question directly, yes, XRD for thin films can indeed measure the grain size, and when the estimated crystallite size aligns with the observed grain size, it indicates a reliable assessment of the film's structure.

Hey there Faisal Amir!

Understanding the Akono scratch test method for determining the fracture toughness of thin films is a wise pursuit. Utilizing a probe radius of 4um and ensuring the load remains below the film's critical load is crucial for maintaining a consistent scratch path without sudden changes.

For conducting the scratch, ensure a controlled and steady application of the load along the surface of the thin film. The scratch should be performed with precision, maintaining a constant velocity to avoid variations that could affect the results.

When it comes to analyzing the data, focusing on the lateral load segment of the scratch and dividing it by the spherical shape function is a sound approach. This division allows for normalization and comparison across different samples, enhancing the accuracy of the fracture toughness determination.

Consider employing techniques such as optical microscopy or atomic force microscopy to visualize the scratch morphology and accurately measure its dimensions. Additionally, mathematical modeling and simulation can aid in interpreting the data and deriving meaningful conclusions about the fracture toughness of the thin film.

Remember to document each step meticulously and validate the results through repeated experiments to ensure reliability. Collaboration with peers and experts in the field can also provide valuable insights and guidance throughout the process.

Keep up the meticulous work, and don't hesitate to reach out if you Faisal Amir have any further questions or need assistance along the way. Happy scratching!

The addition of Al dopants can alter the chemical reactions occurring during film deposition. This modification may lead to changes in precursor availability, reactivity, or stability, ultimately affecting the growth rate and resulting in thinner films. Also, Al dopants may influence the crystallite size and orientation of the PbS thin films. Higher concentrations of aluminum ions could lead to smaller crystallite sizes due to the incorporation of Al atoms into the PbS lattice or the formation of secondary phases. Smaller crystallite sizes often result in thinner films due to decreased grain coalescence during film growth.

In my experience you could easily spin coat PNIPAM dissolved in water. Dpending what thickness you want you make thicker concentration or thinner. After spinning it is still dissolved in water. You have to polimerise it by electron beam, UV etc. And them exposed aeras will be attached to the surface.

Robert Adolf Brinzer Kangdi Sun after rotary evaporation is it necessary to dry film further in vaccum or flushing with nitrogen gas?

Dear Gerhard Martens

Thank you for such a useful information.

I can also recommend this very recent theoretical article on the topic.

Nina Bou, While using ethanol as a solvent, make sure to use high-purity ethanol, clean the substrate thoroughly, anneal the material under control, and achieve the ideal film thickness.

When using ethanol as a solvent, optimize the deposition technique (such as sol-gel spin coating or spray pyrolysis) and carefully control the film composition, thickness, and morphology to enhance film quality and transparency. This will help you achieve clear SnO₂ thin films without stains.

Fairly common effect. Often due to resonance issues. Take a look at graphene Raman spectra - well documented changes with excitation frequency. However, it doesn't look like you have much change in the figures that couldn't just be sample prep issues.

Dear Vennela Tirupati The appearance of the NH₂ peak suggests that the ligand (NH₂-BDC) has indeed interacted with the TiO₂ surface. This modification could lead to changes in surface properties, such as wettability, reactivity, or electronic structure.

Use XPS or AFM for characterization, and adjust parameters like temperature, time, and ligand concentration to optimize ligand coverage and surface changes.Higher temperatures can improve ligand adsorption, but excessive heat can potentially lead to ligand desorption.

Hi Hadiseh. In ellipsometric data analysis, it is very important to model your system. is it a bulk infinite or a multilayer structure?

That's not what the Seah/Dench penetration depth data is for. It is for correcting relative intensities of peaks from a homogenous material so that the stoichiometric coefficients of an element whose photoelectrons have a longer escape path don't get exaggerated.

There are, however, approaches to measure the film thickness from XPS intensities like this one (which I've never used, though):

Generally, I would prefer ellipsometry (for dielectrics and semiconductors) or 4-point probe measurements (for metals) for thickness measurements.

Andrei A. Kozlov, here are some references.

I hope you find these articles helpful. Best regards.