Project

Preparation and characteristics study of Ni/porous silicon and Cd/porous silicon contacts.

Goal:
1. x-ray

2. Dark (i-v) and (c.v)

3. Responsivity

4. quantum efficiency

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Hasan A. Hadi
added a research item
In this work, nanocrystalline porous silicon (PSi) was prepared by the photo-electrochemical etching (PECE) technique. A comparison study between the optoelectronic properties of double junctions Ni/PSi/c-Si and Cd/PSi/c-Si photodetectors is reported. The Ni and Cd thin films were deposited on the porous silicon layers by the thermal evaporation technique. The structural, electrical, and optoelectronic properties of Cd/PSi/n-Si and Ni/PSi/c-Si devices were examined at room temperature. The XRD analysis confirmed the formation of the nanocrystalline structure of the PSi layer. Scanning electron microscope (SEM) studies reveal the formation of circular pores with an average diameter of 250 nm. The dark and illuminated I-V characteristics of the photodetectors are investigated at room temperature, and the junction characteristics of the Cd/PSi/c-Si junction are better than those of the Ni/PSi/c-Si junction. The maximum responsivity of the Cd/PSi/c-Si photodetector is 1.47AW⁻¹ at 400 nm, while the maximum responsivity of Ni/PSi/c-Si was about 1.45AW⁻¹ at 540 nm. The external quantum efficiency (EQE) of Cd/PSi/c-Si and Ni/PSi/c-Si photodetectors was 450% and 330% at 400 nm, respectively.
Hasan A. Hadi
added 2 research items
In this report, laser assisted in electrochemical etching technique PECE to prepare porous silicon layers under the constant conditions was used. To confirm the possibility of using different wavelengths of laser light to control the thickness of structures and porosity of silicon layers, a scanning electron microscope and weight measurements techniques were used to study of morphology of porous surface and its porosity. It was found that the porosity values according to the different wavelengths have same power density approximately and which ranged from 39 to 53% towards the shortest wavelength. The intensity of the integrated peak absorption of Si-H and O-H vibrations demonstrated in the FTIR spectra of these samples was calculated. In this work, optical properties dependence of porous silicon crystalline size is analyzed and correlated to photoluminescence spectra. It's clear that the Photoluminescence PL peak energy was decreasing from 2.37 to 2.10ev, and corresponding the increasing in refractive indexes. The peak PL intensity dropped from short wavelength (blue) toward long wavelength in visible region with large than 50% ratio.
This study focused on the fabrication and characterization of CuS/porous Si heterojunction photodetector prepared by deposition of chemically sprayed CuS film on the porous silicon substrate prepared by anodization method. The optical and structural of CuS film and porous silicon PSi layer were investigated using x-ray diffraction, scanning electron microscope SEM, energy dispersive x-ray EDX, atomic force microscopy AFM, and UV-Vis optical absorption. XRD studies confirm the CuS film deposited on glass substrate was polycrystalline in nature with hexagonal structure, while the XRD data of the CuS film deposited on PSi shows only single peak at 2θ = 27° corresponds to (101) plane. The optical properties results reveal that the direct optical bandgap of CuS was around 2.25 eV. SEM shows that the average wall size and pore size of the porous silicon were 200 nm and 550 nm, respectively, and the CuS film consists of spherical grains with average grain size of 45 nm. AFM data illustrates that the root mean square of surface roughness of CuS film 9.1 nm. PL spectrum of PSi shows a strong emission peak at 576 nm. The optoelectronics properties of CuS/PSi/c-Si photodetector including dark and illuminated I-V characteristics, spectral responsivity, quantum efficiency, and detectivity were measured at room temperature. The responsivity of the photodetectors at peak of response 500 nm was 2.15 A/W.
Hasan A. Hadi
added 2 research items
This paper presents a study of Sn/PS/p-Si heterojunction device which is fabricated by growing Sn thin film onto p-type porous Si substrate by using thermal evaporation deposition and electrochemical etching (ECE) in crystalline p-Si method. Effect etching current density on the morphology of the porous silicon surface is checked using atomic force microscopy AFM. Current–voltage (I–V), capacitance–voltage (C– V) characteristics. The ideality factor and series resistance are found to be large than the one (11.18 and 25 kΩ) respectively by the analysis of the dark I–V characteristics of Sn/PS/p-Si. While the analysis of the dark C–V, the built-in voltage and carrier’s concentrations are found to be 0.59V and 1.1×1017cm-3 respectively. These characteristics are interpreted by assuming the abrupt heterojunction model from C-V measurement. The barrier height potential is measured by both I–V and C–V which is found to be 0.74eV. The Energy band diagram of heterojunction relevant by I-V and C-V measurements is sketched. Keywords: porous silicon, electrochemical etching (ECE), Schottky Barrier, AFM
Novel doped polystyrene (PS)/porous silicon (PSi) heterojunction photodetector prepared by solution cast and electrochemical techniques is proposed here. The structural and optical properties of polystyrene film and porous silicon surface were investigated using X-ray diffraction (XRD), scanning electron microscope, Fourier transformed infrared (FT-IR), and UV–Vis spectrophotometer. XRD data confirmed that the PS film was amorphous in nature and the porous silicon was nanocrystalline. The optical properties showed that the average optical transmittance and the optical energy gap of PS film were 80% and 3.2 eV, respectively. The electrical properties revealed that the electrical resistivity and mobility of the doped polystyrene film were 3 × 10⁴ Ω cm and 4.5 × 10⁻⁵ cm² V⁻¹ s⁻¹, respectively. Photoluminescence PL of porous silicon was investigated. Dark I–V characteristics revealed that the PS/PSi heterojunctions prepared with an etching time of 5 min exhibited better-rectifying properties than that of PS/PSi heterojunction prepared at 10 min. The figures of merit of the photodetectors such as spectral responsivity, external quantum efficiency, and detectivity were investigated and compared with Au/PSi Schottky photodetectors. Minority carrier lifetime of the photodetectors was measured using open circuit voltage decay method.
Hasan A. Hadi
added a project goal
1. x-ray
2. Dark (i-v) and (c.v)
3. Responsivity
4. quantum efficiency