Bashir Ahmmad

Yamagata University | YU · Department of Informatics and Electronics

The influence of multi‐step sintering at high temperatures was used to meticulously characterize the crystallization, mechanical, and optical properties of a SiO2−Li2O−Al2O3−K2O−P2O5${\rm SiO}_2{-}{\rm Li}_2{\rm O}{-}{\rm Al}_2{\rm O}_3{-}{\rm K}_2{\rm O}{-}{\rm P}_2{\rm O}_5$ glass system with the addition of ZrO2${\rm ZrO}_2$ and Y2${\rm Y}_2$O3$...

Nanometer-thick-TiO2-channel thin-film transistors (TFTs) are examined as oxidizing-agent monitors for room-temperature atomic layer deposition (RTALD). RTALD is a plasma-based process using plasma-excited humidified argon where OH radicals oxidize the precursor-gas adsorbed surface. In the TFT, the anatase TiO2 channel, with a thickness of 16 nm,...

Researchers are keenly interested in developing metal‐based nanoparticles using plant sources as they are eco‐friendly, less expensive and simpler. Zinc oxide nanoparticles, symbolized as D‐ZnONPs and M‐ZnONPs were synthesized in this study utilizing the leaves of D. indica and M. micrantha, respectively, and studied their impact on the growth inhi...

The versatile application of metal‐based nanoparticles has led to a recent rise in interest in the low‐cost and eco‐friendly green chemistry‐based development of metal oxide nanoparticles. This work focuses on the photocatalytic and antibacterial uses of the zinc oxide nanoparticles (ZnONPs) that were produced based on a green approach employing st...

Sodium adsorption on nanometer-thick-TiO2-channel thin-film transistors (TFTs) are examined for enhancing the drain current. In the TFTs, the channel thickness of TiO2 is set as thin as ∼16 nm. The TiO2 film is deposited by atomic layer deposition using plasma excited humified Ar, followed by crystallization into the anatase phase by thermal anneal...

Complex oxide films of TiO2 and ZnO are deposited by room-temperature atomic layer deposition (ALD) with a sequential adsorption process. In this ALD, we use a Zn precursor of dimethyl zinc (DMZ) and a Ti precursor of tetrakis(dimethyl)aminotitanium (TDMAT). In the sequential adsorption step, the DMZ saturation on the surface is followed by a parti...

BaTiO 3 (BTO) is widely recognized for its ability to absorb ultraviolet light. To enable the absorption of visible light for photocatalytic water splitting, we modified its band gap energy by...

Multilayer antireflection coatings (ARCs) for solar cells are conventionally designed to enhance the photocurrent level obtained at normal incidence. This is mainly because outdoor solar panels are usually placed such that they can receive strong midday sunlight at a nearly vertical angle. However, in the case of indoor photovoltaic devices, the di...

AlN and Al 2 O 3 multilayer films intended as moisture barriers were deposited on polyethylene naphthalate films by remote-type plasma-enhanced atomic layer deposition. The deposition temperatures for AlN and Al 2 O 3 were 160 and 20 °C, respectively. It was assumed that the AlN and Al 2 O 3 interface would suppress the formation of dislocations an...

The room temperature magnetic hysteresis (M-H) loops reveal ferromagnetic-like behavior in an antiferromagnetically ordered LaFeO (LFO) material system synthesized by the sol–gel method. The maximum magnetization (M) for the undoped sample annealed at 800 °C is 1.08 emu/g, whereas, with the same annealing, materials that are Dy and Y doped (25%) ex...

Low-temperature deposition of Y2O3 at 80°C is studied using an yttrium precursor of tris(butylcyclopentadienyl)yttrium (Y(BuCp)3) and plasma exited humidified argon oxidizer. The deposition is demonstrated using an atomic-layer-deposition sequence; the Y(BuCp)3 and the oxidizing gases are time separately introduced to the reaction chamber and these...

The low temperature deposition of AlN at 160 °C is examined by using trimethyl aluminum (TMA) and NH radicals from plasma excited Ar diluted ammonia. For the deposition, a plasma tube separated from the reaction chamber is used to introduce the neutral NH radicals on the growing surface without the direct impacts of high-speed species and UV photon...

Multiple layers of aluminum silicate and SiO 2 are deposited at room temperature (RT) by repeating a combination of aluminum-silicate atomic layer deposition (ALD) and a plural number of SiO 2 ALDs. The RT-ALD is performed by using precursors of tris(dimethylamino)silane and trimethyl aluminum (TMA). The oxidizing gas is plasma excited humidified A...

Room-temperature atomic layer deposition (RT-ALD) of iron oxide is developed with a precursor of bis(N, N′-diisopropyl-propionamidinate)iron [(DIPPA) 2 Fe] and plasma excited humidified Ar. Saturated conditions of (DIPPA) 2 Fe and plasma excited humidified Ar exposures at room temperature (23–25 °C) are investigated by in situ IR absorption spectro...

Organic molecule (Histidine) embedded cadmium sulfide (CdS) nanocomposites are prepared by the solvothermal method. CdS nanocomposite, prepared with 1:1 M ratio of S²⁻ to Cd²⁺, shows the highest crystallinity and highest hydrogen production via water splitting. Optimization of Pt deposition indicates that 5.5 wt% of Pt deposition on CdS nanocomposi...

Nanothick TiO 2 channel-thin film transistors (TFTs) are examined as UV and gas sensors. The TiO 2 thin films were deposited by atomic layer deposition on thermally oxidized n ⁺ Si substrates with deposition thicknesses from 17 to 42 nm, where the channel length and width were fixed at 60 μ m and 1 mm, respectively. The titanium drain and source el...

We report on the magnetic and optical properties of DyFe0.5Cr0.5O3 nanoparticles synthesized by sol-gel method. Rietveld refinement of powder X-ray diffraction (XRD) pattern confirms the formation of orthorhombic disordered phase with Pnma space group. The formation of nano-sized particles, with an average size of 42(±12) nm, was approximated by th...

Nano crystalline zinc oxide (ZnO) is deposited by room temperature atomic layer deposition (RT-ALD) using dimethylzinc and a plasma excited humidified Ar without thermal treatments. The TEM observation indicated that the deposited ZnO films were crystallized with grain sizes of ∼20 nm on Si in the course of the RT-ALD process. The crystalline ZnO e...

Room-temperature (RT) atomic layer deposition (ALD) of aluminum silicate is developed with a successive adsorption process of tris(dimethylamino)silane (TDMAS) and trimethylaluminum (TMA) using an oxidizer of plasma-excited humidified Ar. The Si-to-Al atomic ratio in the deposited film is controlled by the ratio of TMA and TDMAS exposures. RT depos...

We report the effect of temperature on the crystallographic structure and magnetic properties of ultrasonically prepared nanostructured Nd0.7Sr0.3MnO3 perovskite manganite. The crystal structure of as-synthesized nanoparticles remains unaltered over a wide scanning temperature range. Temperature dependent magnetization measurements demonstrate that...

Pure cadmium sulfide and histidine decorated cadmium sulfide nanocomposites are prepared by the hydrothermal or solvothermal method. Scanning electron microscopy (SEM) analysis shows that the particle sizes of pure cadmium sulfide (pu/CdS) and histidine decorated cadmium sulfide prepared by the hydrothermal method (hi/CdS) range from 0.75 to 3.0 μm...

To improve the efficiency of organic photovoltaics (OPVs), the trapping of incident light with surface nanostructures, such as moth eye structures, is a highly useful strategy for enhancing absorption in the photoactive layer. Nanoimprint lithography is a widely used technique to produce large-area nanostructures cost effectively. However, the moth...

To improve the performance of organic photovoltaics, we investigate an integrated device design in which the hybrid antireflection structure, composed of a surface moth-eye nanotexture and a multilayer interference film, is applied with a high-refractive-index glass substrate. The moth eye texture with a relatively long period, which is near the ba...

Room temperature (RT) atomic layer deposition (ALD) of Nb2O5 is developed using (tert-butylimido)tris(ethylmethylamido)niobium and a plasma excited humidified Ar. To design the process condition, an in situ monitoring system of IR absorption spectroscopy (IRAS) is utilized to observe the surface saturation of precursors. Based on the saturation cha...

In Bangladesh, India, and Pakistan the ship breaking (SB) sector dismantles end-of-life ships on open beaches, exposing the environment to the resulting pollution, especially the soil and water. Because SB occurs in the vicinity of other poorly-regulated activities in industrial zones (IZ) in these countries, there is some ambiguity concerning the...

We report room-temperature atomic layer deposition (ALD) of SnO2 using tetramethyltin (TMT) as a precursor and plasmaexcited humidified argon as an oxidizing gas and investigate the saturation behaviors of these gases on SnO2-covered Si prisms by IR absorption spectroscopy to determine optimal precursor/oxidizer injection conditions. TMT is demonst...

A room-temperature atomic layer deposition (RT-ALD) of aluminum silicate for molecule sorption is developed using trimethylaluminum (TMA) and trismethylaminosilane (TDMAS) using a plasma excited humidified argon. The aluminum-silicate is a main material of zeolites that is used for cation sorption. If we achieved the aluminum silicate deposition on...

The authors present a plasma enhanced room-temperature atomic layer deposition (ALD) technique for depositing aluminum silicate on TiO2 photoanodes for dye-sensitized solar cells. In the ALD process, adsorption of the precursor is completed in a two-step process involving sequential application of a subsaturation quantity of tris(dimethylamino)sila...

A simple route to prepare Gd0:7Sr0:3MnO3 nanoparticles by ultrasonication of their bulk powder materials is presented in this article. For comparison, Gd0:7Sr0:3MnO3 nanoparticles are also prepared by ball milling. The prepared samples are characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), energy dispersi...

We propose a new antireflection (AR) design for organic photovoltaics (OPVs) to achieve broadband and omnidirectional enhancement of photocurrent. In the proposed design, a hybrid AR structure, which combines moth eye texturing and two-layer interference coating, is integrated with a glass substrate having a high refractive index (n). Using the opt...

Core-shell nanoparticles consist of core materials coated with different kinds of films, where new functional material properties are expected by the combination of core and shell materials. In our laboratory, we have been developing the Au-core-oxide-semiconductor shell particles which must be used for the electron channel material. By using the m...

A room-temperature atomic layer deposition (RT-ALD) of Al 2 O 3 as an anticorrosion coating for metal surfaces was developed using trimethylaluminum (TMA) and a plasma excited humidified argon. The schematic of ALD system is shown in Fig.1. TMA as the aluminum precursor was introduced with a mass flow controller. A remote plasma system generating e...

The synthesis as well as structural, multiferroic and optical characterization of Dy doped BiFeO3 multiferroic ceramic are presented. Bulk polycrystalline Bi0.9Dy0.1FeO3 sample is synthesized by solid state reaction, while their nano counterparts are prepared using ultrasonic probe sonication technique. Significant improvement of phase purity in th...

The authors developed a room temperature atomic layer deposition (ALD) system that can deposit TiO2 on gold nanoparticles by using tetrakis(dimethylamino)titanium and plasma-excited humidified argon. The growth per cycle of TiO2 was measured to be 0.25 nm/cycle on a monitored Si sample. For applying the nanoparticle coating, the source material, i....

Sr-substituted perovskites, La1.8Sr0.2MMnO6 (M = Ni, Co), were synthesized using the solid-state reaction technique to present a systematic study on their morphological, structural and magnetic properties. The average grain size of the as-prepared La1.8Sr0.2NiMnO6 samples are in the range of 0.2–0.7 µm and those for La1.8Sr0.2CoMnO6 manganites are...

In this investigation, undoped BiFeO3, Gd doped Bi0.9Gd0.1FeO3, and Gd-Ti co-doped Bi0.9Gd0.1Fe1−xTixO3 (x = 0.10, 0.20) materials were synthesized to report their multiferroic properties. The structural analysis and phase identification of these multiferroic ceramics were performed using Rietveld refinement. The Rietveld analysis has confirmed the...

Dye sensitized solar cells (DSCs) have attracted much attention since the DSCs have cost advantages compared with the conventional Si solar cells. To achieve the high power conversion efficiency in the DSC, it is necessary to enhance the dye adsorption on the TiO 2 nanoparticles. To achieve the high-density adsorption, we examined the TiO 2 coating...

Tin oxide (SnO 2 ) is an oxide semiconductor material with an excellent optical transparency, where it is used as transparent conducting films. It is also used as a channel material for gas sensors. Recently atomic layer deposition (ALD) of SnO 2 has been studied intensively since ALD allows the conformal deposition of the oxide film with an atomic...

Organic photovoltaics (OPVs) are considered to have a great potential to solve future energy supply scenarios due to their advantages such as low production and material costs. The power conversion efficacy and lifetime of bulk heterojunction OPVs have been significantly increasing in the last decade, although further improvements will be required...

To improve the performance of organic photovoltaics (OPVs), it is useful to trap light by using the antireflection nanotexture such as moth eye structure. The finite-difference time-domain (FDTD) method is frequently used to analyze the optical properties of nanotexture. However, in the case that FDTD is applied to OPVs, the existence of a glass su...

Room-temperature atomic layer deposition (ALD) of ZrO2 is developed with tetrakis(ethylmethylamino)zirconium (TEMAZ) and a plasma-excited humidified argon. A growth per cycle of 0.17 nm/cycle at room temperature is confirmed, and the TEMAZ adsorption and its oxidization on ZrO2 are characterized by IR absorption spectroscopy with a multiple interna...

The ceramic pellets of the nominal compositions Bi0.7Ba0.3Fe1−xTixO3 (x = 0.00-0.20) were prepared initially by standard solid state reaction technique. The pellets were then ground into micrometer-sized powders and mixed with isopropanol in an ultrasonic bath to prepare nanoparticles. The X-ray diffraction patterns demonstrate the presence of a si...

Size of semiconductor devices in large-scale integration has reached the submicron range where gate oxide films in metal oxide semiconductor (MOS) devices need to be fabricated at a nanometer scale. Atomic layer deposition (ALD) is a technology for depositing dielectric films with monolayer precision by repeating adsorption of a source gas on subst...

Improvement in magnetic and electrical properties of multiferroic BiFeO3 in conjunction with their dependence on particle size is crucial due to its potential applications in multifunctional miniaturized devices. In this investigation, we report a study on particle size dependent structural, magnetic and electrical properties of sol-gel derived Bi0...

We have prepared Gd and Ti co-doped BiFeO 3 multiferroic nanoparticles by ultrasonication of their bulk powder materials. The starting materials were ceramic pellets of the nominal compositions Bi 0.9 Gd 0.1Fe 1−x Ti x O 3 (x = 0.00–0.20) prepared by a conventional solid state reaction technique [1]. The ceramic pellets sintered at optimum temperat...

ABSTRACT The ceramic pellets of the nominal compositions Bi0.7Ba0:3Fe1-xTixO3 (x = 0.00-0.20) were prepared initially by standard solid state reaction technique . The pellets were then ground into micrometer-sized powders and mixed with isopropanol in an ultrasonic bath to prepare nanoparticles . The crystal structure of the nanoparticles as well a...

The perovskite manganite La2NiMnO6 (LNMO) has attracted considerable research interest in recent years due to their rich physics and potential applications in spintronic devices. Previous investigations demonstrated that doping the initially investigated insulating LaMnO3 material, in which only Mn3+ exists, with the divalent ions Ca, Ba, Sr, etc....

A simple route to prepare Gd 0.7 Sr o.3 MnO 3 nanoparticles by ultrasonication of their bulk powder materials is developed. For comparison Gd 0.7 Sr o.3 MnO 3 nanoparticles were also prepared by ball milling. Transmission Electron Microscopy demonstrated the formation of nanoparticles with average size in the range from 10-30 nm for ultrasonication...

Ceramic pellets of multiferroic Bi 0.90 Dy 0.1 FeO 3 (BDFO) were prepared by a conventional solid state reaction technique [1]. The pellets were then ground into powder by manual grinding. These powder materials were mixed with isopropanol and sonicated for 30-90 minutes using an ultrasonic probe of diameter 13 mm to obtain nanoparticles. The surfa...

Undoped and Gd–doped BiFeO 3 nanoparticles have been synthesized by sol-gel method. The effects of Gd-doping on morphological, ferroelectric and optical properties have been investigated. The particle size of the undoped and Gd-doped BiFeO 3 nanoparticles, estimated using a field emission scanning electron microscopy, has been found to be in the ra...

We have investigated the effect of temperature on magnetic properties of Bi$_{0.9}$Gd$_{0.1}$Fe$_{1-x}$Ti$_x$O$_3$ (x = 0.00-0.20) multiferroic system. Unexpectedly, the coercive fields ($H_{c}$) of this multiferroic system increased with increasing temperature. The coercive fields and remanent magnetization were higher over a wide range of tempera...

We have reported earlier the dielectric and magnetic properties of Gd and Ti co-doped Bi0.9Gd0.1Fe1-xTixO3 (x = 0.00-0.25) ceramics at room temperature prepared by solid state reaction technique [1]. In this investigation, the effect of temperature on magnetic properties of this ceramic system was carried out. The coercive fields (Hc) were increase...

The polycrystalline bulk sample having composition BiFe0.94Li0.06O3 was prepared by using a conventional solid state reaction technique [1]. Then the bulk powder materials sintered at optimum temperature were mixed with isopropanol and the solutions were sonicated for 60 minutes using an ultrasonic bath [2]. The settling time of the solutions was v...

Temperature-controlled ALD of GaN on Si(100) is demonstrated with TMG and plasma-excited NH3. The TMG adsorption and its reaction with NH3 plasma are investigated by IR abosption spectroscopy and X-ray photoelectron spectroscopy. It is found that the TMG saturation has the highest adsorption density at RT and the plasma-excited NH3 is effective in...

To improve the power conversion efficacy of organic photovoltaics (OPVs), it is required to design antireflection structures that could realize efficient and broadband light trapping. In this article, we perform global optimization of the textured pattern of moth eye antireflection surfaces to maximize the short-circuit current density (J SC) of OP...

Fundamental surface reactions in the atomic layer deposition of GaN with trimethylgallium (TMG) and plasma-excited NH3 are investigated by multiple-internal-reflection infrared absorption spectroscopy (MIR-IRAS) at surface temperatures varying from room temperature (RT) to 400°C. It is found that TMG is saturated at RT on GaN surfaces when the TMG...

This article discusses the hydrothermal synthesis of well-dispersed faceted α-GaOOH in the presence of sodium acetate by the self-assembly method. The synthesized α-GaOOH possesses a mixture of hexagonal and rectangular plates, cubic and diamond-like morphologies. The presence of ethanol as a co-solvent with water (1:1) facilitates scroll-like cyli...

The exchange bias (EB) effect has been observed in magnetic Bi0.9Gd0.1Fe0.9Ti0.1O3 nanoparticles. The influence of magnetic field cooling on the exchange bias effect has also been investigated. The magnitude of the exchange bias field (HEB) increases with the cooling magnetic field, showing that the strength of the exchange bias effect is tunable b...

The exchange bias (EB) effect has been observed in magnetic Bi$_{0.9}$Gd$_{0.1}$Fe$_{0.9}$Ti$_{0.1}$O$_3$ nanoparticles. The influence of magnetic field cooling on the exchange bias effect has also been investigated. The magnitude of the exchange bias field ($H_{EB}$) increases with the cooling magnetic field, showing that the strength of the excha...

Aluminum oxide (Al2O3) is well known as an oxide coating material. Al2O3 is also used as a barrier layer preventing water moisture and oxygen for organic light emitting diodes (OLEDs) [1]. Al2O3 has been also studied as an anticorrosion coating material [2]. On the other hand, Al2O3 has been studied as a passivation layer for Si solar cells [3]. Th...

This work proposes hybrid antireflection (AR) structure that integrates moth eye texturing and multi-layer interference coating for application to organic solar cells (OSCs). We conduct nearly global optimization of the geometric parameters (i.e., the period and height of moth eye array and the thicknesses of interference layers) for the hybrid AR...

Gallium oxide is expected as a channel material for thin film transistors. In the conventional technologies, gallium oxide has been tried to be fabricated by atomic layer deposition (ALD) at high temperatures from 100-450 °C, although the room-temperature (RT) growth has not been developed. In this work, we developed the RT ALD of gallium oxide by...

Nitrogen adsorption on thermally cleaned Si (100) surfaces by pure and plasma excited NH3 is investigated by in situ IR absorption spectroscopy and ex-situ X-ray photoelectron spectroscopy with various temperatures from RT (25°C) to 800°C and with a treatment time of 5 min. The nitrogen coverage after the treatment varies according to the treatment...

Facile and eco-friendly methods have been developed for the fabrication of ultrafine nanoparticles of iron based oxides. Initially, mesoporous α-Fe 2 O 3 nanoparticles were prepared by the green tea mediated hydrothermal method. The nanoparticles of α-Fe 2 O 3 were highly pure and well crystallized with an average particle size of 60 nm. For the fa...

Aluminum oxide (Al 2 O 3 ) is well known as an oxide coating material. Al 2 O 3 is also used as a barrier layer preventing water moisture and oxygen for organic light emitting diodes (OLEDs) [1]. Al 2 O 3 has been also studied as an anticorrosion coating material [2]. On the other hand, Al 2 O 3 has been studied as a passivation layer for Si solar...

Organic photovoltaics (OPVs) have been receiving growing interest, because they can provide large area and low cost solar cells for next generation. A power conversion efficiency (PCE) of more than 10 % under AM 1.5 illumination has been reported for the OPVs, although higher level of PCE is required for large-scale commercialization. Since the max...

The perovskite manganite La2CoMnO6 (LCMO) has attracted considerable research interest in recent years due to their rich physics and potential applications in spintronic devices. Previous investigations demonstrated that doping the initially investigated insulating LaMnO3 material, in which only Mn3+ exists, with the divalent ions Ca, Ba, Sr, etc....

Magnetic properties of manganites at the nanometer scale are currently the focus of intense investigations due to their potential technological applications. When the size of the magnetic particles is reduced to a few tens of nanometer, they exhibit fascinating physical properties e.g. spin-glass behavior, spontaneous magnetization, giant magnetore...

Multiferroic materials, BiFeO 3 with the rhombohedrally distorted perovskite structure is the most promising since it can exhibit (anti) ferroelectricity, (anti) ferromagnetism, and/or ferroelasticity in the same phase at room temperature. This extraordinary behavior make them potential candidate in data storage, the emerging field of spintronics,...

Multiferroic materials exhibit simultaneous presence of (anti)ferroelectricity, (anti)ferromagnetism, and/or ferroelasticity in the same phase and have attracted considerable research interest due to their potential applications in data storage, emerging field of spintronics, switchable spin valves, high frequency filters and sensors. Among the lim...