Does ion Bombardment Induce a Degradation of the Electronic Properties of a-Si:H Films?

1990 ◽  
Vol 192 ◽  
Author(s):  
P. Roca i Cabarrocas ◽  
P. Morin ◽  
J. Conde ◽  
V. Chu ◽  
J.Z. Liu ◽  
...  
Keyword(s):  
Glow Discharge ◽  
Electronic Properties ◽  
Valence Band ◽  
Ion Bombardment ◽  
Clear Correlation ◽  
Negative Bias ◽  
Substrate Bias ◽  
Band Tail ◽  
Ion Energy

ABSTRACTWe present a detailed study of the effects of a negative bias applied to the substrate on the electronic properties of a-Si:H films deposited by r.f. glow discharge. Two series of samples deposited at 30 and 100 mTorr respectively have been studied. For each series the negative d.c. bias applied to the substrate was decreased from 0 to −100 V in steps of 25 V. We observe for both series of samples an improvement of the electronic properties of the films as we decrease the substrate bias (increase the ion energy) down to − 50 V. We have found a clear correlation between the negative bias applied to the substrate and the subgap absorption, the valence band tail slope and the electron and hole μτ products.

Stress Modification in Tungsten Films Deposited by Ion-Assisted Evaporation

1988 ◽  
Vol 128 ◽  
Author(s):  
R. A. Roy ◽  
R. Petkie ◽  
D. S. Yee ◽  
J. Karasinski ◽  
A. Boulding
Keyword(s):  
Ion Bombardment ◽  
Film Stress ◽  
Clear Correlation ◽  
Original Structure ◽  
Qualitative Behavior ◽  
X Ray Diffraction ◽  
Ion Energy ◽  
X Ray ◽  
Impurity Model ◽  
The Relationship

ABSTRACTThe modification of film stress in evaporated tungsten was studied as a function of deposition environment. Using concurrent ion bombardment of the growing film, the stress was seen to vary systematically with ion energy, ion flux, and substrate temperature. The qualitative behavior fits the model of stress modification developed for niobium films. X-ray diffraction was used to study the structure of the films, and a clear correlation between crystallographic texture and film stress is found. The original structure/impurity model for film stress modification due to ion bombardment has been modified to account for the relationship between film stress and texture.

States in the Gap of Improved a-Ge:H Studied by Photomodulation Spectroscopy

1991 ◽  
Vol 219 ◽  
Author(s):  
L. Chen ◽  
J. Tauc ◽  
D. Pang ◽  
W. A. Turner ◽  
W. Paul
Keyword(s):  
Glow Discharge ◽  
Valence Band ◽  
Density Of States ◽  
Pump Beam ◽  
Defect Density ◽  
Dangling Bond ◽  
Band Tail ◽  
Valence Bands

ABSTRACTThe photomodulation spectra of a-Ge:H of average photoelectronic quality(ημπ = 1 × 10-10cm2/V) and of improved quality (ημπ = 3 × 10-7cm2/V), produced under different plasma conditions in an r.f. diode reactor by glow discharge, were measured at 80K and are analyzed in analogy with earlier studies of a-Si:H. The spectra of the poorer material are dominated by transitions between dangling bond states and the conduction and valence bands. By contrast, the spectra of the better material require contributions of transitions from the band tail states, indicating that the reduced defect density has resulted in pump-beam induced quasi-Fermi levels reaching near the conduction and valence band edges. A very acceptable fit between plausible density-of-states distributions and the experimental spectra has been found.

Detailed Study of Ion Bombardment in Rf Glow Discharge Deposition Systems: The Role of Helium Dilution

1989 ◽  
Vol 149 ◽  
Author(s):  
P. Roca I Cabarrocas
Keyword(s):  
Glow Discharge ◽  
Effective Means ◽  
Ion Bombardment ◽  
Electrostatic Energy ◽  
Ion Energy ◽  
Capacitively Coupled ◽  
Ion Energy Distribution ◽  
Reactor Geometry ◽  
Rf Glow Discharge ◽  
Argon Dilution

ABSTRACTWe present a detailed study of the variables (reactor geometry, gas pressure, rf power and silane dilution) which control the flux and energy of the ions impinging on the substrate in capacitively-coupled rf glow discharge systems. The ion flux and ion energy, measured with an electrostatic energy analyzer, were found to be largely dependent on the reactor geometry, which was quantified by the ratio of the area of the grounded surfaces Sg to the area of the rf electrode Sc. Special attention was paid to the effects of the dilution of silane in hydrogen, helium and argon. Helium and hydrogen dilution were found the most effective means to increase ion bombardment while argon dilution has little effect on the ion energy distribution. Furthermore, it is likely that ion bombardment at moderate energy (Eion < 70 eV) does not induce any serious degradation of the electronic properties of a-Si:H films.

Substrate bias effects during R-F sputtering of Y-Ba-Cu-O films

1990 ◽  
Vol 5 (4) ◽  
pp. 677-679 ◽  
Author(s):  
A. J. Drehman ◽  
M. W. Dumais
Keyword(s):  
Thin Films ◽  
Strontium Titanate ◽  
Reactive Sputtering ◽  
Negative Bias ◽  
Superconducting Thin Films ◽  
Substrate Bias ◽  
Composition Control ◽  
Zero Resistance

Y-Ba-Cu-O films were made by R-F diode sputtering using a single oxide target. It was found that if a small negative bias is applied to the substrate, the etching associated with reactive sputtering is significantly reduced. This results in better composition control and uniformity, which are quite important for the formation of superconducting thin films. Films deposited on strontium titanate, when annealed in oxygen, become superconducting with zero resistance at 89 K.

scholarly journals Electron yield of glow discharge cathode materials under helium ion bombardment

1988 ◽  
Vol 53 (5) ◽  
pp. 358-360 ◽  
Author(s):  
B. Szapiro ◽  
J. J. Rocca ◽  
T. Prabhuram
Keyword(s):  
Glow Discharge ◽  
Cathode Materials ◽  
Ion Bombardment ◽  
Electron Yield ◽  
Helium Ion

Ion Bombardment Effect on the Hardness of Ti(C,N,O) Films Prepared by Ion Beam Controlled Deposition (IBCD)

1992 ◽  
Vol 279 ◽  
Author(s):  
Chen Youshan ◽  
Sun Yilin ◽  
Zhang Fumin ◽  
Mou Haichuan ◽  
Tao Wei ◽  
...  
Keyword(s):  
Film Formation ◽  
Ion Beam ◽  
Ion Bombardment ◽  
Advanced Technology ◽  
Preferential Growth ◽  
Ion Energy ◽  
Lattice Constants ◽  
Film Hardness ◽  
Pure Compounds ◽  
Controlled Deposition

Ion beam controlled deposition (IBCD) or ion beam assisted deposition (IB AD) of Ti(C,N,O) films has been investigated much in the last decade for both the advantage of this advanced technology and the promising properties of such materials. Ti(C,N,O) films are various solid solutions of interstitial compounds TiC, TiN and TiO of F.C.C structure with lattice constants lying between the values of the pure compounds. Some content of oxygen improves their wear resistance due to the lower fn;e enthalpies of such films in comparison with pure TiC and TiN films [1]. Many so-synthesizcd titanium carbide and titanium nitride films reported in published papers were actually of this sort as they often had more or less oxygen content from residual gas in vacuum. A number of papers were contributed to depict the texture and composition dependence of film on the arrival ratio of assisting ions versus deposited atoms (AR) as well as their mechanical properties [2–6]. However, the film formation mechanism in IBCD isn't quite clear yet, especially for cases with assisting ion energy of several to tens of keV. During a course to synthesize Ti(C,N,O) films by IBCD with the two beam technique, datum were accumulated. Based on a part of it, a previous paper on ion beam governed preferential growth in IBCD has been published [7]. This paper was aimed to search for the origin of ion bombardment effect on film hardness.

Sensitization of the Holes Lifetime by the Addition of Dangling Bonds in a-Si:H

2001 ◽  
Vol 664 ◽  
Author(s):  
L.F. Fonseca ◽  
S. Z. Weisz ◽  
I. Balberg
Keyword(s):  
Valence Band ◽  
Important Implication ◽  
Dangling Bond ◽  
Dangling Bonds ◽  
Defect States ◽  
Band Tail ◽  
Present Understanding

ABSTRACTThis paper is concerned with the phenomenon of the increase of the holes lifetime with the increase of the dangling bond concentration in a-Si:H. This rather surprising phenomenon that was observed, but not discussed, previously is shown to be a non-trivial effect which is based on the charged nature of the dangling bonds and a special scenario of the concentrations of the various defect states in the material. The most important implication of our study is that the charged dangling bonds can sensitize the valence band tail states, in contrast with the accepted roles of these types of states. The present understanding suggests that many new interesting phototransport phenomena can be found in a-Si:H.

Sign in / Sign up

Export Citation Format

Share Document