Toward the Elimination of Light-Induced Degradation of Amorphous Si by Fluorine Incorporation

1992 ◽  
Vol 258 ◽  
Author(s):  
X. Deng ◽  
E. Mytilineou ◽  
R. T. Young ◽  
S. R. Ovshinsky
Keyword(s):  
Glow Discharge ◽  
Amorphous Silicon ◽  
Density Of States ◽  
Deposition Temperature ◽  
Gas Mixture ◽  
Dangling Bonds ◽  
Material Stability ◽  
Saturated State ◽  
High Deposition Temperature ◽  
Amorphous Si

ABSTRACTWe report on evidence that fluorine, properly incorporated into a-Si, replaces weakly bonded hydrogen and improves the material stability under light soaking. Our fluorinated amorphous silicon (a-Si:H:F) is made by if glow discharge at high deposition temperatures up to 430 C from a gas mixture of SiH4 or Si2H6 and F2. These a-Si:H:F films show much lower density of states in the light soaking saturated state than device quality a-Si:H prepared in the same deposition system. It is evident from our results that fluorine incorporated into the network at such high deposition temperature makes for a new configuration which minimizes dangling bonds and other defects.

Electronic Transport and the Density of States Distribution in a-(Si, Ge):H, F Alloys

1986 ◽  
Vol 70 ◽  
Author(s):  
S. Aljishi ◽  
Z E. Smith ◽  
D. Slobodin ◽  
J. Kolodzey ◽  
V. Chu ◽  
...  
Keyword(s):  
Optical Properties ◽  
Glow Discharge ◽  
Amorphous Silicon ◽  
Density Of States ◽  
Electronic Transport ◽  
Silicon Germanium ◽  
Drift Mobility ◽  
Electronic And Optical Properties ◽  
Reported Data ◽  
Amorphous Silicon Germanium

ABSTRACTThe electronic and optical properties of amorphous silicon-germanium alloys produced by d.c. and r.f. glow discharge are reported. Data on the sub-gap absorption, dark and photo conductivities, drift mobilities and drift mobility-lifetime products are used to propose a density of states model.

Photoelectronic Properties of a-Si:Sex and a-Si:Tex Thermally Evaporated Films.

1986 ◽  
Vol 70 ◽  
Author(s):  
F. G. Wakim
Keyword(s):  
Activation Energy ◽  
Solar Cells ◽  
Glow Discharge ◽  
Amorphous Silicon ◽  
Thermal Activation ◽  
Thermal Activation Energy ◽  
Dangling Bonds ◽  
Optical Gap ◽  
Si Films

ABSTRACTThe presence of selenium (Se) or Telurium (Te) in amorphous silicon films seems to improve the quality of these films by reducing the number of unsatisfied or dangling bonds and changing the optical gap and thermal activation energy. The thermal activation energies of a-Si:Sex and a-Si:Tex were always larger than that of a-Si films. The measured optical gap can be tailored to some value between 0.8 eV and 1.8 eV depending on the use of Se or Te and on the relative concentrations. The presence of Se or Te in a-Si films seems to have the same effect as that of hydrogen in a-Si films prepared by glow discharge of silane and used in solar cells.

Indirect Diffusion Mechanism of Boron Atoms in Crystalline and Amorphous Silicon

2008 ◽  
Vol 1070 ◽  
Author(s):  
Salvo Mirabella ◽  
Davide De Salvador ◽  
Enrico Napolitani ◽  
Elena Bruno ◽  
Giuliana Impellizzeri ◽  
...  
Keyword(s):  
Experimental Design ◽  
Amorphous Silicon ◽  
Thermal History ◽  
Diffusion Mechanism ◽  
Dangling Bonds ◽  
Defect Interaction ◽  
First Case ◽  
Diffusion Parameters ◽  
Amorphous Si ◽  
Positively Charged

ABSTRACTThe diffusion of B atoms in crystalline and amorphous Si has been experimentally investigated and modeled, evidencing the indirect mechanism of these mass transport phenomena. The migration of B occurs after interaction with self-interstitials in crystalline Si (c-Si) or with dangling bonds in amorphous Si (a-Si). In the first case, an accurate experimental design and a proper modeling allowed to determine the microscopic diffusion parameters as the B-defect interaction rate, the reaction paths leading to the diffusing species and its migration length. Moreover, by changing the Fermi level position, B atoms are shown to interact preferentially with neutral or doubly positively charged self-interstitials. As far as the amorphous case is concerned, B diffusion is revealed to have a marked transient character and to depend on the B concentration itself. In particular, boron atoms can move after the interaction with dangling bonds whose density is transiently increased after ion implantation or permanently enhanced by the presence of boron atoms themselves. Unexpectedly, B diffusivity in a-Si is seen to be orders of magnitude above than in c-Si and to depend on the thermal history, i.e. the relaxation status of the amorphous phase. These data are presented and their implications discussed.

Effects of deposition temperature on properties of r.f. glow discharge amorphous silicon thin films

1991 ◽  
Vol 205 (2) ◽  
pp. 140-145 ◽  
Author(s):  
E. Bertran ◽  
J.L. Andújar ◽  
A. Canillas ◽  
C. Roch ◽  
J. Serra ◽  
...  
Keyword(s):  
Thin Films ◽  
Glow Discharge ◽  
Amorphous Silicon ◽  
Deposition Temperature ◽  
Silicon Thin Films

Density-of-States Distribution In Disilane LPCVD Deposited Amorphous Silicon as Determinated By SCLC

1986 ◽  
Vol 70 ◽  
Author(s):  
C. Manfredotti ◽  
G. Gervino ◽  
L. Montaldi ◽  
R. Varesio ◽  
A. Zanini ◽  
...  
Keyword(s):  
Fermi Level ◽  
Amorphous Silicon ◽  
Density Of States ◽  
Hydrogen Content ◽  
Deposition Temperature ◽  
Direct Method ◽  
A Direct Method ◽  
Deposited Films

ABSTRACTI-V characteristics have been measured in a-Si:H films deposited from Si2 H6 by LPCVD and have been analyzed according to a direct method. DOS distribution is thickness-dependent, similarly to what has been found on SiH deposited films, with values at Fermi level ranging from below 1016 cm-3 eV-1 up to 1018 cm-3 eV-1. Deposition temperature, at least in the interval 450 - 500°C, does not seem to affect DOS distribution. Hydrogen content is pratically constant in all the films. The only possible conclusion is that only thickness influences DOS distribution and that only for thickness larger than 0.8 μm it is possible to get densities at Fermi level below 1016 cm-3 eV-1.

Density of states in amorphous silicon produced by microwave glow discharge

1982 ◽  
Vol 53 (1) ◽  
pp. 439-441 ◽  
Author(s):  
M. Aktik ◽  
J. F. Currie ◽  
A. Yelon
Keyword(s):  
Glow Discharge ◽  
Amorphous Silicon ◽  
Density Of States

Mobility-Lifetime Products in Glow Discharge and RF Sputter Deposited A-Si:H

1994 ◽  
Vol 336 ◽  
Author(s):  
M. H. Farias ◽  
A. Roche ◽  
S. Z. Weisz ◽  
H. Jia ◽  
J. Shinar ◽  
...  
Keyword(s):  
Light Intensity ◽  
Glow Discharge ◽  
Comparative Study ◽  
Deposition Temperature ◽  
Charge Carriers ◽  
Dangling Bonds ◽  
Majority Carrier ◽  
Recombination Processes ◽  
Pool Model ◽  
Sputter Deposited

ABSTRACTA comparative study of the deposition temperature (Ts) dependence of the Mobility-lifetime (μτ) products of the charge carriers in glow-discharge and rf sputter-deposited a-Si:H is described and discussed. The Ts-dependence of the μτ's the majority carrier light-intensity exponents of the two types of films are strikingly similar. These observations lead to the conclusion that the structure of the recombination levels as well as the recombination processes are in accord with the “defect pool” Model, in contrast to previous suggestions. The differences between the two types of films thus appear to be limited to the differences in the concentrations of dangling bonds.

Metastable Defects in the Amorphous Silicon-Germanium Alloys

2003 ◽  
Vol 762 ◽  
Author(s):  
J. David Cohen
Keyword(s):  
Amorphous Silicon ◽  
Silicon Germanium ◽  
Dangling Bonds ◽  
Annealing Behavior ◽  
Fundamental Properties ◽  
Silicon Materials ◽  
Salient Features ◽  
The Individual ◽  
Amorphous Silicon Germanium ◽  
Silicon Germanium Alloys

AbstractThis paper first briefly reviews a few of the early studies that established some of the salient features of light-induced degradation in a-Si,Ge:H. In particular, I discuss the fact that both Si and Ge metastable dangling bonds are involved. I then review some of the recent studies carried out by members of my laboratory concerning the details of degradation in the low Ge fraction alloys utilizing the modulated photocurrent method to monitor the individual changes in the Si and Ge deep defects. By relating the metastable creation and annealing behavior of these two types of defects, new insights into the fundamental properties of metastable defects have been obtained for amorphous silicon materials in general. I will conclude with a brief discussion of the microscopic mechanisms that may be responsible.

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