Reduction of Neutral Dangling Bond Density by Light Soaking in Nanocrystalline Silicon

1998 ◽  
Vol 507 ◽  
Author(s):  
Takahiro Matsumoto ◽  
Yasuaki Masumoto ◽  
Michio Kondo
Keyword(s):  
Electron Spin Resonance ◽  
Defect Density ◽  
Light Exposure ◽  
Reduction Rate ◽  
Nanocrystalline Silicon ◽  
Dangling Bond ◽  
Bond Density ◽  
Spin Resonance ◽  
Neutral Defect ◽  
Nanocrystalline Si

ABSTRACTThe effects of light exposure on neutral defect density at the surface of nanocrystalline Si are investigated by electron-spin resonance (ESR) experiments. A decrease of the neutral dangling bond density by light soaking was observed in this nanostructure. The reduction rate of ESR signal intensity becomes large with increasing light exposure intensity, and the reduction occurs from the excitation energy higher than 2 eV in vacuum. The reduction of the defect density can be explained in terms of the conversion of neutral states to charged states by carrier trapping.

Light-Soaking Effects on Photoconductivity in a-Si:H Thin Films

1997 ◽  
Vol 467 ◽  
Author(s):  
E. Morgado ◽  
M. Rebelo da Silva ◽  
R. T. Henriques
Keyword(s):  
Thin Films ◽  
Defect Density ◽  
Light Exposure ◽  
Dangling Bond ◽  
Photothermal Deflection Spectroscopy ◽  
Spin Resonance ◽  
Photo Conductivity ◽  
Photothermal Deflection ◽  
Gap States ◽  
Induced Defects

ABSTRACTMetastable defects have been created by light exposure in thin films of a-Si:H. The samples have been characterized by Photothermal Deflection Spectroscopy, Electron Spin Resonance, dark- and photo-conductivity. The experimental results are consistent with numerical calculations with a recombination model involving band tails and one class of correlated dangling-bond states. The effects of light-soaking on the ligh intensity and defect density dependences of photoconductivity are reproduced by the calculations. The model allows to explain the experimental trends by changes in the electronic occupation of the gap states produced by light-induced defects.

CORRELATION BETWEEN OPTICAL DEFECT DENSITY AND SPIN DENSITY IN AMORPHOUS SILICON CARBIDE

1991 ◽  
Vol 05 (04) ◽  
pp. 285-292 ◽  
Author(s):  
F. DEMICHELIS ◽  
C.F. PIRRI ◽  
E. TRESSO
Keyword(s):  
Silicon Carbide ◽  
Absorption Coefficient ◽  
Amorphous Silicon ◽  
Defect Density ◽  
Dangling Bond ◽  
Amorphous Silicon Carbide ◽  
Bond Density ◽  
Spin Resonance ◽  
Excess Absorption ◽  
Deposition Conditions

Amorphous silicon carbide (a-SiC:H) films deposited by different techniques under different deposition conditions have been submitted to photo-thermal deflection and photoacoustic spectroscopy (PDS and PAS) and electron spin resonance (ESR) measurements in order to obtain, through the trend of low energy absorption coefficient and the density of spins, information on the nature, energy and number of defects. The results obtained from the two techniques are often in disagreement since the dangling bond density generally does not scale with the integrated defect density. In order to explain the discrepancy the absorption coefficient has been calculated, following the Tauc model, in the three regions of fundamental absorption, Urbach tail and excess absorption. An expression for the density of defects has been obtained which depends on the integrated excess absorption coefficient through a proportionality factor.

Simultaneous Relaxation of Network and Defects in Silicon-Implanted a-Si:H

1995 ◽  
Vol 377 ◽  
Author(s):  
J. Nakata ◽  
S. Sherman ◽  
S. Wagner ◽  
P. A. Stolk ◽  
J. M. Poate
Keyword(s):  
Electronic Transport ◽  
Annealing Temperature ◽  
Urbach Energy ◽  
Defect Density ◽  
Dark Conductivity ◽  
Equilibrium Theory ◽  
Hopping Conduction ◽  
Dangling Bond ◽  
Bond Density ◽  
Additional Illumination

ABSTRACTWe report extensive optical and electronic transport data on silicon-implanted a-Si:H, annealed in steps in the dark or with additional illumination. All measured properties relax gradually with increasing annealing temperature. The dark conductivity of the as-implanted film is dominated by hopping conduction via midgap defects. This channel is pinched off during the initial stages of annealing. The midgap defect density and the Urbach energy follow an annealing path that agrees qualitatively with the trajectory postulated by the equilibrium theory of the dangling-bond density. Therefore, the silicon network and the defect density equilibrate continuously during network relaxation.

scholarly journals INVESTIGATIONS INTO ELECTRON SPIN RESONANCE IN DOPED NANOCRYSTALLINE SILICON FILMS

2001 ◽  
Vol 50 (3) ◽  
pp. 512
Author(s):  
LIU XIANG-NA ◽  
XU GANG-YI ◽  
SUI YUN-XIA ◽  
HE YU-LIANG ◽  
BAO XI-MAO
Keyword(s):  
Electron Spin Resonance ◽  
Electron Spin ◽  
Nanocrystalline Silicon ◽  
Silicon Films ◽  
Spin Resonance ◽  
Nanocrystalline Silicon Films

The Effects of Hydrogen Profiling and of Light-Induced Degradation on the Electronic Properties of Hydrogenated Nanocrystalline Silicon

2005 ◽  
Vol 862 ◽  
Author(s):  
A.F. Halverson ◽  
J.J. Gutierrez ◽  
J.D. Cohen ◽  
Baojie Yan ◽  
Jeffrey Yang ◽  
...  
Keyword(s):  
Electronic Properties ◽  
Minority Carrier ◽  
Defect Density ◽  
Light Exposure ◽  
Nanocrystalline Silicon ◽  
Drive Level ◽  
Dramatic Decrease ◽  
Transient Photocurrent ◽  
Hydrogen Dilution ◽  
Carrier Collection

AbstractThe electronic properties of hydrogenated nanocrystalline silicon (nc-Si:H) were studied using junction capacitance methods. Drive-level capacitance profiling (DLCP) measurements revealed significant differences for nc-Si:H layers deposited under constant hydrogen dilution compared to those deposited using hydrogen profiling, with lower DLCP densities in the latter case. Transient photocapacitance (TPC) measurements revealed the mixed-phase nature of these materials. It disclosed spectra that appeared quite microcrystalline-like at lower temperatures, but more similar to a-Si:H at higher temperatures where the minority carrier collection is higher in the nanocrystalline component of these samples. This then suppresses the TPC signal from this component compared to the a-Si:H component. In contrast, because transient photocurrent signals are enhanced by the additional minority carrier collection, those spectra appear microcrystalline like at all temperatures. We also investigated the effects of light-induced degradation in these devices. This caused a dramatic decrease in hole collection, similar to that caused by reducing the measurement temperature of the samples. However, the light exposure did not appear to increase the deep defect density (dangling bonds).

Correlation Between Freeze-In Temperature of Defect Density and Hydrogen Concentration in a-Si:H

1991 ◽  
Vol 219 ◽  
Author(s):  
X. Xu ◽  
M. Isomura ◽  
J. H. Yoon ◽  
S. Wagner ◽  
J. R. Abelson
Keyword(s):  
Hydrogen Concentration ◽  
Defect Density ◽  
Dangling Bond ◽  
Bond Density ◽  
Higher Temperature ◽  
Defect Densities

ABSTRACTWe measured the freeze-in temperature of the dangling-bond density in a-Si:H in nine samples with hydrogen concentrations ranging from 7.0 to 31 at.%. The measurements were made by determining the defect density of samples quenched from successively higher temperature. We determined the defect densities with the constant photoconductivity method. The freeze-in temperature is 211±10 °C, and is independent of hydrogen concentration.

Defect and Tail States in Microcrystalline Silicon investigated by pulsed ESR

2000 ◽  
Vol 609 ◽  
Author(s):  
P. Kanschat ◽  
H. Mell ◽  
K. Lips ◽  
W. Fuhs
Keyword(s):  
Electron Spin Resonance ◽  
Detailed Analysis ◽  
Electron Spin ◽  
Qualitative Model ◽  
Dangling Bond ◽  
Microcrystalline Silicon ◽  
Band Tail ◽  
Spin Resonance ◽  
Donor States ◽  
Broad Structure

ABSTRACTWe report on a detailed analysis of paramagnetic states in a doping series of microcrystalline silicon, μc-Si:H, by pulsed electron spin resonance. We identify two dangling bond like structures at g = 2.0052 (db1) and g = 2.0043 (db2). Whereas db1 is evenly distributed in the gap, the db2 state is found to be localized in the lower part of the gap. The CE resonance at g ≈ 1.998 is assigned to electrons in conduction band tail states. In p-doped samples, we observe a broad structure CH at g ≈ 2.08 which we identify with holes trapped in valence band tail states. It is shown that the CH state behaves very similar on illumination as the CE resonance. In n-type samples a pair of hyperfine split lines (A ≈ 11 mT) is found which apparently does not originate from 31P-donor states. On the basis of our results we propose a qualitative model for paramagnetic states in μc-Si:H.

The Interpretation of the Constant Photocurrent Method in Terms of Deep Defect Density of States in A-SI.H

1994 ◽  
Vol 336 ◽  
Author(s):  
Frank Siebke ◽  
Helmut Stiebig
Keyword(s):  
Electron Spin Resonance ◽  
Photoelectron Spectroscopy ◽  
Defect Density ◽  
Total Yield ◽  
Calibration Factor ◽  
Optical Transitions ◽  
Absolute Value ◽  
Spin Resonance ◽  
Pool Model

ABSTRACTThe constant photocurrent Method (CPM) is often used to measure the sub-bandgap absorption for the determination of the defect density. However, the absolute value of the derived defect density depends on the method of data analysis and the calibration factor. Normally the calibration factor is obtained from electron spin resonance (ESR) but the defect pool model gives rise to doubt whether ESR detects the same defects as CPm. Therefore, we propose combined total-yield photoelectron spectroscopy (TYPES) and CPM Measurements on n-type a-Si:H to determine the calibration factor. Furthermore, we calculate CPM spectra by extending an approach to simulate photoconductivity, taking into account the full set of optical transitions, and compare the results with standard evaluation Methods.

Sign in / Sign up

Export Citation Format

Share Document