16 research outputs found
Photo-electrochemically synthesized light emtting nanoporous silicon based UV photodetector: influence of current density
Nanoporous silicon (n-PSi) with diverse morphologies was prepared on silicon (Si) substrate via photo-electrochemical etching technique. The role of changing current density (15, 30 and 45 mA cm−2) on the structure, morphology and optical properties was determined. As-prepared samples were systematically characterized using XRD, FESEM, AFM and photoluminescence measurements. Furthermore, the achieved n-PSi sample was used to make metal–semiconductor–metal (MSM) UV photodetector. The performance of these photodetectors was evaluated upon exposing to visible light of wavelength 530 nm (power density 1.55 mW cm−2), which exhibited very high sensitivity of 150.26 with a low dark current. The achieved internal photoconductive gain was 2.50, the photoresponse peak was 1.23 A W−1 and the response time was 0.49 s and the recovery time was 0.47 s. Excellent attributes of the fabricated photodetectors suggest that the present approach may provide a cost effective and simple way to obtain n-PSi suitable for sundry applications
Photophysical performance of radio frequency sputtered Pt/n-PSi/ZnO NCs/Pt photovoltaic photodetectors
The effect of the annealing temperature on the photoelectrical properties of the nanoporous silicon/zinc oxide nanocrystallites-based (Pt/n-PSi/ZnO NCs/Pt) photodetector was investigated. Different morphologies of 3D ZnO were synthesized onto the n-PSi substrates via radio frequency (RF) sputtering in the absence of a catalyst. The synthesis of ZnO NCs was controlled by varying the growth temperature between 600–700 °C and 800–900 °C. The effect of the synthesis temperature on the structural, morphological, and optical properties of the n-PSi/ZnO NCs was systematically studied using field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), atomic force microscopy (AFM), and photoluminescence spectroscopy (PL) techniques. The roughness was found to be dependent on the anodization current density. The optimal n-PSi/ZnO NCs-based metal-semiconductor-metal UV detector (MSM) was fabricated at 700 °C. The fabricated device showed a high sensitivity of 1007.14, an internal photoconductive gain of 11.07, and a responsivity of 5.99 A/W with a low dark current when illuminated with 380 nm light (1.55 mW/cm2) at +5 V bias voltage. In addition, the response and recovery times were determined to be 0.34 and 0.22 s, respectively. This approach offers a cost-effective substrate and simple synthesis method to improve the growth of the n-PSi/ZnO NCs and demonstrates the successful fabrication of nanoscale photodetectors with potential application in nano-optics devices
Doping GaN NPs Synthesized by a Chemical Method for p-n Junction Application
This research was devoted to studying the doping of GaN NPs at low temperature with Mg and the possibility of using them in the p-n junction. This study was subjected to a FESEM, EDX, XRD, PL and Hall Effect examination. The FESEM examination showed clear images of the NPs, the XRD peaks appear at 2? = 32.5, 39.1 and 45.48 which conform the crystalline of p-GaN NPs, Hole Effects measurements confirm the p-GaN with different Mg ratios. The ideality factor and series resistance of p-n junction have been measured
Photophysical performance of Nd-YAG annealed Pt/n-PSi /Pt photovoltaic photodetectors at different laser energy
This study investigates the electrical and photoresponse properties of Nd-YAG annealed Pt/n-PSi/Pt photodetectors. A porous silicon (PSi) layer was deposited on a single crystalline n-type Si via photoelectrochemical etching in aqueous hydrofluoric acid at 45 mA cm−2 for 30 min. Annealing of the n-PSi layer was conducted using a Q-switching Nd:YAG laser at different fluence laser energies (20, 30, 40, 60 mJ cm−2) with a pulse duration of 10 ns. The effect of Nd:YAG laser irradiation on the morphological and structural properties of the deposited n-PSi layer was determined. The n-PSi sample synthesized at 40 mJ cm−2 showed the maximum average discrepancy. The photodetectors fabricated using such materials showed very high sensitivity (1527.9) and low dark current (2.58 × 10−4 A) with an internal photoconductive gain of 16.27, photoresponse of 3.1 A W−1, response time of 0.29 s, and recovery time of 0.45 s. These exceptional properties of the fabricated photodetectors indicate that the laser annealing approach is a viable tool for the synthesis of n-PSi that is suitable for various applications
Low-Temperature Solution-Processed Flexible Solar Cells Based on (In,Ga)N Nanocubes
Indium
gallium nitride nanocubes were syntheized via a low-temperature
chemical route. Energy-dispersive X-ray spectroscopy and X-ray diffraction
analyses confirmed the successful fabrication of (In,Ga)N with various
indium mole fractions. The bandgap of the material was tunded as a
function of the indium content. The fabricated nanocubes showed a
deep level photoluminescence emission at 734 nm as well as in the
visible region at 435–520 nm. The Hall effect measurements
showed the hole concentration to constantly increase from 6.2 ×
10<sup>16</sup> to 2.3 × 10<sup>18</sup> cm<sup>–3</sup>, while the hole mobility to decrease from 0.92 to 0.1 cm<sup>2</sup> /(V s) as the doping ratio increases from 0.005 to 0.025 cm<sup>–3</sup>. The solar cell device made of nanocubes film containing
0.4 indium on flexible substrates showed a short-circuit current density
of 12.47 mA/cm<sup>2</sup> and an open-circuit voltage (<i>V</i><sub>oc</sub>) of 0.48 V with 54% fill factor. The relationship between <i>V</i><sub>oc</sub> and indium content in the fabricated films
was also investigated
Laser annealing enhanced the photophysical performance of Pt/n-PSi/ZnO/Pt-based photodetectors
High-performance nanoporous silicon-based photodetectors
A series of porous silicon (PSi) samples was prepared using photoelectrochemical etching (PECE) method with optimum current density of 45 mA/cm2. The as-prepared PSi samples were characterized to determine the influence of the etching time (15, 25 and 30 min) on their morphology and electrical properties. The percentage of porosity was estimated via gravimetric analysis. The band gap of the fabricated PSi was ≈2.22 eV. Upon their use to fabricate metal-semiconductor-metal (MSM) ultraviolet photodetectors (UVPD), the fabricated PSi revealed excellent stability and reliability under repetitive shots at 530 nm. Furthermore, very fast rise time (≈0.28 s) was obtained at a bias of 1 V under visible light (530 nm) illumination