Thermal Quenching of Photoconductivity and the Sign of Photocarriers in Doped a-Si:H

1991 ◽  
Vol 219 ◽  
Author(s):  
B.-G. Yoon ◽  
H. Fritzsche ◽  
M. Q. Tran ◽  
D.-Z. Chi
Keyword(s):  
Light Intensity ◽  
Cross Section ◽  
Capture Cross Section ◽  
Thermal Quenching ◽  
Capture Cross ◽  
Present Evidence ◽  
Normal Cross Section ◽  
Recombination Centers ◽  
P Type ◽  
Minority Carriers

ABSTRACTThermal quenching (TQ) of photoconductivity σp occurs when the demarkation level of minority carriers passes through recombination centers having small capture cross section for majority carriers compared to other centers present but normal cross section for minority carriers. The photoconductivity becomes superlinear with light intensity at the temperature of maximum TQ. We discovered TQ not only in n-type but also p-type a-Si:H. This cannot happen with the same centers unless the sign of the majority carriers changes. We present evidence that in p-type and undoped films majority carriers are electrons at T below TQ and holes above TQ. The nature of these special centers will be discussed.

Grain Boundary Passivation in Polycrystalline Silicon : A D.L.T.S. Study

1981 ◽  
Vol 5 ◽  
Author(s):  
Prakash C. Srivastava ◽  
Jacques C. Bourgoin
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Cross Section ◽  
Polycrystalline Silicon ◽  
Capture Cross Section ◽  
Narrow Band ◽  
Total Density ◽  
Capture Cross ◽  
Deuterium Plasma ◽  
P Type

ABSTRACTAfter treatment in a deuterium plasma, the D.L.T.S. spectrum associated with grain boundaries in p–type Si is found to reduce to a narrow band centered at 0.32 ± 0.02 eV with a total density of 5 ⨉ 1015 cm−2 . However, the capture cross-section, measured to be ∼ 2 × 10−20 cm2 , is 10 times larger than the apparent cross-section associated with the states present in unpassivated material.

Shallow and Deep Levels in Al+-Implanted p-Type 4H-SiC Measured by Thermal Admittance Spectroscopy

2015 ◽  
Vol 821-823 ◽  
pp. 403-406 ◽  
Author(s):  
Koutarou Kawahara ◽  
Hiroshi Watanabe ◽  
Naruhisa Miura ◽  
Shuhei Nakata ◽  
Satoshi Yamakawa
Keyword(s):  
Cross Section ◽  
Ionization Energy ◽  
Capture Cross Section ◽  
Deep Levels ◽  
Admittance Spectroscopy ◽  
Capture Cross ◽  
Shallow Acceptor ◽  
Wide Range ◽  
Emission Time ◽  
P Type

Shallow and deep levels in SiC significantly affect dynamic characteristics of SiC devices; larger ionization energy and/or a smaller capture cross-section of levels in the SiC bandgap lead to a larger emission time constant and slower response of carriers. Nevertheless, knowledge about those levels is very limited. In this study, we clarified the ionization energy and the capture cross section of the Al shallow acceptor in 4H-SiC in a wide range of doping concentration by preparing appropriate samples and measuring them by thermal admittance spectroscopy. Furthermore, high densities of deep levels were discovered in Al+-implanted samples, which can degrade 4H-SiC device performance without any care.

Dislocation States and Deformation-Induced Point Defects in Plastically Deformed Germanium

2009 ◽  
Vol 156-158 ◽  
pp. 289-294 ◽  
Author(s):  
S. Shevchenko ◽  
A.N. Tereshchenko
Keyword(s):  
Heat Treatment ◽  
Cross Section ◽  
Point Defects ◽  
Capture Cross Section ◽  
Main Type ◽  
Narrow Line ◽  
Capture Cross ◽  
P Type ◽  
Ionization Enthalpy ◽  
Dlts Spectra

We used the DLTS and photoluminescence (PL) techniques to study the deep states due to dislocations and deformation-induced point defects (PDs) in plastically deformed p-type germanium single crystals containing predominantly 60 dislocations with density ND, ranging from 105 to 106 cm-2. The narrow line near the temperature 140K dominates in the DLTS spectra. The ionization enthalpy and the capture cross section for holes traps indicate that the substitution copper atoms Cus are the main type of PDs. A decrease of the Cus atoms concentration and redistribution of the intensity in the PL spectra after the heat treatment of deformed samples at a temperature 500 °C are attributed to the diffusion of copper atoms to dislocations resulting in the appearance of “dirty” regular segments of 60 dislocations.

scholarly journals Nickel and gold identification in p-type silicon through TDLS: a modeling study

2021 ◽  
Vol 93 (4) ◽  
pp. 40101
Author(s):  
Sarra Dehili ◽  
Damien Barakel ◽  
Laurent Ottaviani ◽  
Olivier Palais
Keyword(s):  
Cross Section ◽  
Carrier Lifetime ◽  
Minority Carrier ◽  
Minority Carrier Lifetime ◽  
Defect Level ◽  
Temperature Dependent ◽  
Lifetime Measurements ◽  
Recombination Centers ◽  
P Type ◽  
Minority Carriers

In Silicon, impurities introduce recombination centers and degrade the minority carrier lifetime. It is therefore important to identify the nature of these impurities through their characteristics: the capture cross section σ and the defect level Et. For this purpose, a study of the bulk lifetime of minority carriers can be carried out. The temperature dependence of the lifetime based on the Shockley-Read-Hall (SRH) statistic and related to recombination through defects is studied. Nickel and gold in p-type Si have been selected for the SRH lifetime modeling. The objective of the analysis is to carry out a study to evaluate gold and nickel identification prior to temperature-dependent lifetime measurements using the microwave phase-shift (μW-PS) technique. The μW-PS is derived from the PCD technique and is sensitive to lower impurity concentrations. It has been shown that both gold and nickel can be unambiguously identified from the calculated TDLS curves.

Light Induced Modulation of Absorption (LIMA) of CdS Crystals

1969 ◽  
Vol 24 (9) ◽  
pp. 1306-1310 ◽  
Author(s):  
K.W. Böer
Keyword(s):  
Energy Spectrum ◽  
Optical Absorption ◽  
Cross Section ◽  
High Intensity ◽  
Capture Cross Section ◽  
Optical Excitation ◽  
Frequency Factor ◽  
Capture Cross ◽  
Wide Wavelength Range ◽  
Recombination Centers

Abstract With chopped high intensity optical excitation a modulation of the optical absorption in a wide wavelength-range in CdS was observed. This light induced modulation of absorption is attributed to a redistribution of carriers over levels in the band gap following the chopping frequency. With this method the energy spectrum of certain traps and recombination centers can be determined and their frequency factor and capture cross section obtained. This method permits also the analysis of fast recombination centers.

Thermal Quenching and Photo-Enhancement of μτ Products in a-Si:H - The Role of Dangling Bonds and Band Tails

1994 ◽  
Vol 336 ◽  
Author(s):  
E. Morgado
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Capture Cross Section ◽  
Thermal Quenching ◽  
Capture Cross ◽  
Dangling Bond ◽  
Temperature Dependences ◽  
Capture Cross Sections ◽  
Band Tails

ABSTRACTResults from numerical calculations with a recombination model involving one class of correlated dangling-bond states and exponential band tails, in a-Si:H, are reported. Fermi level, light intensity and temperature dependences of the μτ products are studied. The results are consistent with experimental data. It is found that photo-enhancement of (μτ)e, or superlinear photoconductivity, as well as thermal quenching, are associated with a capture cross section of the band tails smaller than the capture cross sections of the dangling-bond states.

Sign in / Sign up

Export Citation Format

Share Document