Doping Mechanism in Tetrahedral Amorphous Carbon

1997 ◽  
Vol 498 ◽  
Author(s):  
C W Chen ◽  
J Robertson
Keyword(s):  
Amorphous Silicon ◽  
Amorphous Carbon ◽  
Hydrogenated Amorphous Silicon ◽  
Donor Atom ◽  
Dangling Bond ◽  
Coulombic Repulsion ◽  
Tetrahedral Amorphous Carbon ◽  
Total Energies ◽  
Doping Mechanism ◽  
Hydrogenated Amorphous

ABSTRACTDoping in hydrogenated amorphous silicon occurs by a process of an ionised donor atom partially compensated by a charged dangling bond. The total energies of various dopant and dopant/bonding combinations are calculated for tetrahedral amorphous carbon. It is found that charged dangling bonds are less favoured because of the stronger Coulombic repulsion in ta-C. Instead the dopants can be compensated by weak bond states in the lower gap associated with odd-membered π-rings or odd-numbered π-chains. The effect is that the doping efficiency is low but there are not charged midgap recombination centres, to reduce photoconductivity or photoluminescence with doping, as occurs in a-Si:H.

scholarly journals Calorimetry of dehydrogenation and dangling-bond recombination in several hydrogenated amorphous silicon materials

2006 ◽  
Vol 73 (8) ◽  
Author(s):  
P. Roura ◽  
J. Farjas ◽  
Chandana Rath ◽  
J. Serra-Miralles ◽  
E. Bertran ◽  
...  
Keyword(s):  
Amorphous Silicon ◽  
Hydrogenated Amorphous Silicon ◽  
Dangling Bond ◽  
Silicon Materials ◽  
Hydrogenated Amorphous

Observation of slow dangling-bond relaxation inp-type hydrogenated amorphous silicon

1995 ◽  
Vol 51 (4) ◽  
pp. 2173-2179 ◽  
Author(s):  
Martin W. Carlen ◽  
Yueqin Xu ◽  
Richard S. Crandall
Keyword(s):  
Amorphous Silicon ◽  
Hydrogenated Amorphous Silicon ◽  
Dangling Bond ◽  
Hydrogenated Amorphous

Electronic states and total energies in hydrogenated amorphous silicon

1982 ◽  
Vol 25 (2) ◽  
pp. 1065-1080 ◽  
Author(s):  
Douglas C. Allan ◽  
J. D. Joannopoulos ◽  
William B. Pollard
Keyword(s):  
Amorphous Silicon ◽  
Hydrogenated Amorphous Silicon ◽  
Electronic States ◽  
Total Energies ◽  
Hydrogenated Amorphous

Configurational Relaxation of the D Defect in Hydrogenated Amorphous Silicon as a Function of Fermi Energy

1992 ◽  
Vol 258 ◽  
Author(s):  
Thomas M. Leen ◽  
Randall J. Rasmussen ◽  
J. David Cohen
Keyword(s):  
Amorphous Silicon ◽  
Fermi Energy ◽  
Thermal Emission ◽  
Scaling Law ◽  
Hydrogenated Amorphous Silicon ◽  
Dangling Bond ◽  
Universal Scaling ◽  
Depletion Width ◽  
Hydrogenated Amorphous ◽  
Optical Evidence

ABSTRACTBy using light soaking and partial dark annealing to vary the Fermi level in n-type a-Si:H, we have examined the thermal emission of electrons from the dangling bond (D) defect. We find optical evidence for a change in the configuration of the D defect when EF = Ec-0.55±0.08eV. We find that the relaxation rate increases with temperature and increases as EF is brought closer to Ec. Voltage-pulse photocapacitance and depletion-width-modulated ESR show emission is predominantly from D° defects for short emission times and short filling pulse widths. With longer emission times and longer filling pulse widths, emission from D-dominates. We also find that the charge emission transient fits a universal scaling law under a variety of pulsing conditions, temperatures, and anneal states.

Dangling-Bond Relaxation and Metastability in P-Type Hydrogenated Amorphous Silicon

1995 ◽  
Vol 377 ◽  
Author(s):  
Richard S. Crandall ◽  
Martin W. Carlen ◽  
Klaus Lips ◽  
Yueqin Xu
Keyword(s):  
Elevated Temperature ◽  
Amorphous Silicon ◽  
Hydrogenated Amorphous Silicon ◽  
Type A ◽  
Dangling Bond ◽  
Dangling Bonds ◽  
Hole Trapping ◽  
P Type ◽  
Hydrogenated Amorphous

ABSTRACTWe discuss the subtle effects involved in observing slow dangling bond relaxation by studying capacitance transients in p-type hydrogenated amorphous silicon (a-Si:H). The data suggest that neutral dangling bonds are reversibly converted into metastable positive charged dangling bonds by hole trapping. These metastable positive dangling bonds reconvert to neutral dangling bonds upon annealing at elevated temperature. The annealing kinetics for this process are the same as those observed for annealing of quenched in conductivity changes in p-type a-Si:H.

Inadequacy of the Conventional View of Hydrogenated Amorphous Silicon

1986 ◽  
Vol 70 ◽  
Author(s):  
D. Adler ◽  
M. Silver ◽  
M. P. Shaw ◽  
V. Cannella
Keyword(s):  
Amorphous Silicon ◽  
Hydrogenated Amorphous Silicon ◽  
Intrinsic Defect ◽  
Dangling Bond ◽  
Defect States ◽  
Band Tail ◽  
Conventional View ◽  
Substitutional Doping ◽  
Hydrogenated Amorphous ◽  
Basic Experimental Data

ABSTRACTThe conventional view of the electronic structure of hydrogenated amorphous silicon is: (1) the material is characterized by a mobility gap of about 1.8 eV, with exponential band tails due to disorder and deep defect states arising from silicon dangling bonds (T3 centers); (2) substitutional doping occurs because of the formation of chargedimpurity/dangling-bond pairs, e.g. P4+ – T3-, at the substrate temperature; (3) the effective correlation of the T3 center is about 0.4 eV; (4) T3o centers are the predominant recombination center; (5) the three intrinsic ESR signals are due to electrons on T3o centers, electrons in the conduction band tail, and holes in the valence band tail. It is the purpose of this paper to demonstrate that this model is in sharp disagreement with an array of basic experimental data, and much of the evidence presented in its favor is based on self-inconsistent logic. We conclude that it is very likely that large concentrations of charged intrinsic defect pairs are present in all hydrogenated amorphous silicon films.

scholarly journals Impurity-Defect Complexes in Hydrogenated Amorphous Silicon

1990 ◽  
Vol 209 ◽  
Author(s):  
Lin H. Yang ◽  
C. Y. Fong ◽  
Carol S. Nichols
Keyword(s):  
Amorphous Silicon ◽  
Defect Density ◽  
Hydrogenated Amorphous Silicon ◽  
Dangling Bond ◽  
Defect Complexes ◽  
Amorphous Network ◽  
Pseudopotential Calculations ◽  
Impurity Defect ◽  
Supercell Model ◽  
Hydrogenated Amorphous

ABSTRACTThe two most outstanding features observed for dopants in hydrogenated amorphous silicon (a-Si:H) - a shift in the Fermi level accompanied by an increase in the defect density and an absence of degenerate doping - have previously been postulated to stem from the formation of substitutional dopant-dangling bond complexes. Using firstprinciples self-consistent pseudopotential calculations in conjunction with a supercell model for the amorphous network and the ability of network relaxation from the first-principles results, we have studied the electronic and structural properties of substitutional fourfoldcoordinated phosphorus and boron at the second neighbor position to a dangling bond defect. We demonstrate that such impurity-defect complexes can account for the general features observed experimentally in doped a-Si:H.

scholarly journals Material Parameters in a Thick Hydrogenated Amorphous Silicon Detector and their Effect on Signal Collection

1989 ◽  
Vol 149 ◽  
Author(s):  
S. Qureshi ◽  
V. Perez-Mendez ◽  
S. N. Kaplan ◽  
I. Fujieda ◽  
G. Cho
Keyword(s):  
Amorphous Silicon ◽  
Defect Density ◽  
Hydrogenated Amorphous Silicon ◽  
Silicon Detector ◽  
Dangling Bond ◽  
Material Parameters ◽  
Bond Density ◽  
Transient Photoconductivity ◽  
Signal Collection ◽  
Hydrogenated Amorphous

ABSTRACTTransient photoconductivity and ESR measurements were done to relate the ionized dangling bond density and the spin density of thick hydrogenated amorphous silicon (a-Si:H) detectors. We found that only a fraction (∼30–35%) of the total defect density as measured by ESR is ionized when the detector is biased into deep depletion. The measurements on annealed samples also show that this fraction is about 0.3. An explanation based on the shift of the Fermi energy is given. The measurements show that the time dependence of relaxation is a stretched exponential.

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