Saturation behavior of the Light-Induced Defect Density in Hydrogenated Amorphous Silicon

1990 ◽  
Vol 192 ◽  
Author(s):  
H. R. Park ◽  
J. Z. Liu ◽  
P. Roca i Cabarrocas ◽  
A. Maruyama ◽  
M. Isomura ◽  
...  
Keyword(s):  
Amorphous Silicon ◽  
Room Temperature ◽  
Urbach Energy ◽  
Defect Density ◽  
Generation Rate ◽  
Carrier Generation ◽  
Defect Generation ◽  
Ion Laser ◽  
Hydrogenated Amorphous ◽  
Defect Densities

ABSTRACTUsing a Kr ion laser (λ = 647.1 nm) to produce a carrier generation rate G of 3 × 1020 cm−3s−1, we have saturated the light-induced defect generation in hydrogenated (and fluorinated) amorphous silicon (a-Si:H(F)), within a few hours near room temperature. While the defect generation rate scales roughly with 1/G2, the saturation defect densities Ns,sat are essentially independent of G. The saturation is not due to thermal annealing. We have further measured Ns,sat m 37 a-Si:H(F) films grown in six different reactors under different conditions. The results show that Ns,sat lies between 5 × 1016 and 2 × 1017 cm−3, that Ns,sat drops with decreasing optical gap and hydrogen content, and that Ns,sat is not correlated with the initial defect density or with the Urbach energy.

Effect of Deposition-Induced Annealable Defects on Light-Induced Defect Generation in a-Si:H

1993 ◽  
Vol 297 ◽  
Author(s):  
Jong-Hwan Yoon
Keyword(s):  
Amorphous Silicon ◽  
Defect Density ◽  
Hydrogenated Amorphous Silicon ◽  
Generation Rate ◽  
Defect Generation ◽  
Saturated State ◽  
Microscopic Models ◽  
Hydrogenated Amorphous ◽  
Substrate Temperatures

In this paper we present a method to determine the annealable defect density(ΔNann) present in hydrogenated amorphous silicon(a-Si:H). The effects of the annealable defects on the light-induced defect generation rate, saturated defect density (Nsat) and the change of defect density in the light-induced saturated state(ΔNsat) have been studied. Annealable defect density was varied by depositing samples at various substrate temperatures or by post-growth anneals of samples grown at low substrate temperatures. It is found that the generation rate, N satand ΔNsat are well correlated with ΔNann. In particular, the ΔNsat is found to follow a relation ΔNsat ≈ ΔNann. These results suggest that defect-related microscopic models are appropriate for light-induced metastability.

scholarly journals Temperature-Dependent Open-Circuit Voltage Measurements and Light-Soaking in Hydrogenated Amorphous Silcon Solar Cells

2005 ◽  
Vol 862 ◽  
Author(s):  
Jianjun Liang ◽  
E. A. Schiff ◽  
S. Guha ◽  
B. Yan ◽  
J. Yang
Keyword(s):  
Solar Cells ◽  
Amorphous Silicon ◽  
Room Temperature ◽  
Open Circuit Voltage ◽  
Hydrogenated Amorphous Silicon ◽  
Open Circuit ◽  
Illumination Intensity ◽  
Temperature Dependent ◽  
Defect Generation ◽  
Hydrogenated Amorphous

AbstractWe present temperature-dependent measurements of the open-circuit voltage VOC(T) in hydrogenated amorphous silicon nip solar cells prepared at United Solar. At room-temperature and above, VOC measured using near-solar illumination intensity differs by as much as 0.04 V for the as-deposited and light-soaked states; the values of VOC for the two states converge below 250 K. Models for VOC based entirely on recombination through deep levels (dangling bonds) do not account for the convergence effect. The convergence is present in a model that assumes the recombination traffic in the as-deposited state involves only bandtails, but which splits the recombination traffic fairly evenly between bandtails and defects for the light-soaked state at room-temperature. Recombination mechanisms are important in understanding light-soaking, and the present results are inconsistent with at least one well-known model for defect generation.

Dependence of Steady-State Defect Density in Hydrogenated Amorphous Silicon on Carrier Generation Rate Studied Over a Wide Range

1993 ◽  
Vol 297 ◽  
Author(s):  
Nobuhiro Hata ◽  
Gautam Ganguly ◽  
Akihisa Matsuda
Keyword(s):  
Steady State ◽  
Amorphous Silicon ◽  
Defect Density ◽  
Hydrogenated Amorphous Silicon ◽  
Continuous Light ◽  
Effective Rate ◽  
Defect States ◽  
Carrier Generation ◽  
Wide Range ◽  
Hydrogenated Amorphous

Measurements of the steady-state defect density (Nst) in hydrogenated amorphous silicon under illumination of pulse-laser light, as well as of continuous light, were carried out; and the dependence of Nst on the effective rate of carrier generation (G) is presented. The values of G ranged from 8 x 1021 to 2.4 × 1023 cm-3 s-1, while the illumination temperature was kept at 30 °C or at 105 °C. The results showed trends of Nst increasing with G similarly to the trends in the literature, but covered a higher and wider G range, and fitted a defect model which assumes a limited number of possible defect states.

Room-temperature electroluminescence of Er-doped hydrogenated amorphous silicon

1998 ◽  
Vol 227-230 ◽  
pp. 1164-1167 ◽  
Author(s):  
Oleg Gusev ◽  
Mikhail Bresler ◽  
Alexey Kuznetsov ◽  
Vera Kudoyarova ◽  
Petr Pak ◽  
...  
Keyword(s):  
Amorphous Silicon ◽  
Room Temperature ◽  
Hydrogenated Amorphous Silicon ◽  
Er Doped ◽  
Hydrogenated Amorphous

The Spectral Dependence of the Non-Radiative Efficiency in Hydrogenated Amorphous Silicon

1992 ◽  
Vol 258 ◽  
Author(s):  
J. Fan ◽  
J. Kakalios
Keyword(s):  
Amorphous Silicon ◽  
Room Temperature ◽  
Hydrogenated Amorphous Silicon ◽  
Free Carrier ◽  
Radiative Efficiency ◽  
Sharp Minimum ◽  
Carrier Thermalization ◽  
Hydrogenated Amorphous ◽  
Kinetics Of ◽  
Heat Released

ABSTRACTThe room temperature non-radiative efficiency, defined as the ratio of the heat released per absorbed photon for doped and undoped hydrogenated amorphous silicon (a-Si:H) has been measured using photo-pyroelectric spectroscopy (PPES) for photon energies ranging from 2.5 to 1.6 eV. There is a fairly sharp minimum in the non-radiative efficiency when the a-Si:H is illuminated with near bandgap photons. We describe a model wherein this minimum arises from the variation in the amount of heat generated by free carrier thermalization as the incident photon energy is varied, and report measurements of the excitation kinetics of the non-radiative efficiency which support this proposal.

Annealing Kinetics of Amorphous Silicon Alloy Solar Cells Made at Various Deposition Rates

2001 ◽  
Vol 664 ◽  
Author(s):  
Baojie Yana ◽  
Jeffrey Yanga ◽  
Kenneth Lord ◽  
Subhendu Guha
Keyword(s):  
Solar Cells ◽  
Solar Cell ◽  
Amorphous Silicon ◽  
High Frequency ◽  
Room Temperature ◽  
Defect Density ◽  
Very High Frequency ◽  
Solar Cell Performance ◽  
Kinetics Of ◽  
Very High

ABSTRACTA systematic study has been made of the annealing kinetics of amorphous silicon (a-Si) alloy solar cells. The cells were deposited at various rates using H2 dilution with radio frequency (RF) and modified very high frequency (MVHF) glow discharge. In order to minimize the effect of annealing during light soaking, the solar cells were degraded under 30 suns at room temperature to quickly reach their saturated states. The samples were then annealed at an elevated temperature. The J-V characteristics were recorded as a function of annealing time. The correlation of solar cell performance and defect density in the intrinsic layer was obtained by computer simulation. Finally, the annealing activation energy distribution (Ea) was deduced by fitting the experimental data to a theoretical model. The results show that the RF low rate solar cell with high H2 dilution has the lowest Ea and the narrowest distribution, while the RF cell with no H2 dilution has the highest Ea and the broadest distribution. The MVHF cell made at 8Å/s withhigh H2 dilution shows a lower Ea and a narrower distribution than the RF cell made at 3 Å/s, despite the higher rate. We conclude that different annealing kinetics plays an important role in determining the stabilized performance of a-Si alloy solar cells.

scholarly journals Numerical Design of Ultrathin Hydrogenated Amorphous Silicon-Based Solar Cell

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
F. X. Abomo Abega ◽  
A. Teyou Ngoupo ◽  
J. M. B. Ndjaka
Keyword(s):  
Solar Cells ◽  
Solar Cell ◽  
Amorphous Silicon ◽  
Buffer Layer ◽  
Defect Density ◽  
Hydrogenated Amorphous Silicon ◽  
Theoretical Work ◽  
Silicon Based ◽  
The Impact ◽  
Hydrogenated Amorphous

Numerical modelling is used to confirm experimental and theoretical work. The aim of this work is to present how to simulate ultrathin hydrogenated amorphous silicon- (a-Si:H-) based solar cells with a ITO BRL in their architectures. The results obtained in this study come from SCAPS-1D software. In the first step, the comparison between the J-V characteristics of simulation and experiment of the ultrathin a-Si:H-based solar cell is in agreement. Secondly, to explore the impact of certain properties of the solar cell, investigations focus on the study of the influence of the intrinsic layer and the buffer layer/absorber interface on the electrical parameters ( J SC , V OC , FF, and η ). The increase of the intrinsic layer thickness improves performance, while the bulk defect density of the intrinsic layer and the surface defect density of the buffer layer/ i -(a-Si:H) interface, respectively, in the ranges [109 cm-3, 1015 cm-3] and [1010 cm-2, 5 × 10 13  cm-2], do not affect the performance of the ultrathin a-Si:H-based solar cell. Analysis also shows that with approximately 1 μm thickness of the intrinsic layer, the optimum conversion efficiency is 12.71% ( J SC = 18.95   mA · c m − 2 , V OC = 0.973   V , and FF = 68.95 % ). This work presents a contribution to improving the performance of a-Si-based solar cells.

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