Dangling-bond levels and structure relaxation in hydrogenated amorphous silicon

Biswas, R; Li, Q; Yoon, Y; Branz, H M

doi:10.1103/PhysRevB.56.9197

Title: Dangling-bond levels and structure relaxation in hydrogenated amorphous silicon

Full Record
Other Related Research

Abstract

Tight-binding molecular-dynamics calculations are utilized to study the spatial extent and time scales of the structure relaxation, following a change of the charge state of dangling bonds in hydrogenated amorphous silicon. Structural relaxation is found to be local, primarily involving large displacements ({gt}0.1{Angstrom}) of the nearest neighbors of the dangling bond and of a few nearby H atoms. Calculated optical transition levels have the D{sup {minus}} level below both D{sup 0} levels and the D{sup +} level above the D{sup 0} levels. A smooth energy surface is found for transitions between the neutral and charged dangling-bond configurations. Molecular-dynamics simulations show that electron levels relax in tens of picoseconds following electron capture or emission by a dangling bond, but large oscillations of the gap levels may be present as a result of the strong coupling between the charge and local structure. The results do not appear to support either the slow relaxation model of Cohen, Leen, and Rasmussen, or the D structural memory model of Branz and Fedders. {copyright} {ital 1997} {ital The American Physical Society}

Authors:

Biswas, R; Li, Q; Yoon, Y ^[1]; Branz, H M ^[2]

Department of Physics and Astronomy, Microelectronics Research Center and Ames Laboratory, U.S. Department of Energy, Iowa State University, Iowa 50011 (United States)
National Renewable Energy Laboratory, 1617 Cole Boulevard, Golden, Colorado 80401 (United States)

Publication Date:: Wed Oct 01 00:00:00 EDT 1997

Research Org.:: National Renewable Energy Lab. (NREL), Golden, CO (United States)

OSTI Identifier:: 543809

DOE Contract Number:: AC36-83CH10093; W-7405-ENG-82

Resource Type:: Journal Article

Journal Name:: Physical Review, B: Condensed Matter

Additional Journal Information:: Journal Volume: 56; Journal Issue: 15; Other Information: PBD: Oct 1997

Country of Publication:: United States

Language:: English

Subject:: 36 MATERIALS SCIENCE; SILICON; AMORPHOUS STATE; CHEMICAL BONDS; MOLECULAR DYNAMICS METHOD; RELAXATION; SEMICONDUCTOR MATERIALS; CHARGE STATES; HYDROGENATION

Citation Formats


                    Biswas, R, Li, Q, Yoon, Y, and Branz, H M. Dangling-bond levels and structure relaxation in hydrogenated amorphous silicon.  United States: N. p., 1997. 
        Web.  doi:10.1103/PhysRevB.56.9197.

Copy to clipboard


                    Biswas, R, Li, Q, Yoon, Y, & Branz, H M. Dangling-bond levels and structure relaxation in hydrogenated amorphous silicon.  United States.  https://doi.org/10.1103/PhysRevB.56.9197

Copy to clipboard


                    Biswas, R, Li, Q, Yoon, Y, and Branz, H M. 1997.  
        "Dangling-bond levels and structure relaxation in hydrogenated amorphous silicon".  United States.  https://doi.org/10.1103/PhysRevB.56.9197.

Copy to clipboard


                    
@article{osti_543809,

  title        = {Dangling-bond levels and structure relaxation in hydrogenated amorphous silicon},

  author       = {Biswas, R and Li, Q and Yoon, Y and Branz, H M},

  abstractNote = {Tight-binding molecular-dynamics calculations are utilized to study the spatial extent and time scales of the structure relaxation, following a change of the charge state of dangling bonds in hydrogenated amorphous silicon. Structural relaxation is found to be local, primarily involving large displacements ({gt}0.1{Angstrom}) of the nearest neighbors of the dangling bond and of a few nearby H atoms. Calculated optical transition levels have the D{sup {minus}} level below both D{sup 0} levels and the D{sup +} level above the D{sup 0} levels. A smooth energy surface is found for transitions between the neutral and charged dangling-bond configurations. Molecular-dynamics simulations show that electron levels relax in tens of picoseconds following electron capture or emission by a dangling bond, but large oscillations of the gap levels may be present as a result of the strong coupling between the charge and local structure. The results do not appear to support either the slow relaxation model of Cohen, Leen, and Rasmussen, or the D structural memory model of Branz and Fedders. {copyright} {ital 1997} {ital The American Physical Society}},

  doi          = {10.1103/PhysRevB.56.9197},

  url          = {https://www.osti.gov/biblio/543809},
  journal      = {Physical Review, B: Condensed Matter},
number       = 15,

  volume       = 56,

  place        = {United States},

  year         = {Wed Oct 01 00:00:00 EDT 1997},

  month        = {Wed Oct 01 00:00:00 EDT 1997}

}

Copy to clipboard

Journal Article:

https://doi.org/10.1103/PhysRevB.56.9197

Other availability

Find in Google Scholar

Search WorldCat to find libraries that may hold this journal

Save / Share:

Export Metadata

Save to My Library

Similar records in OSTI.GOV collections:

Local structural changes around charged dangling bonds

Book Biswas, R; Li, Q

Tight-binding total energy calculations are used to describe the changes in local structure following either electron or hole capture by a neutral dangling bond in computer generated a-Si:H models. After the change in charge state, the structure is allowed to relax by a steepest descent energy minimization procedure. Generally the local bond angles increase (decrease) rapidly by 3-10{sup 0} in transitions from the D{sup 0} to the D{sup +} (D{sup {minus}}) configurations. The displacement of nearest neighbor atoms and nearby H atoms is large (more than 0.2 {angstrom}), but displacement of distant atoms is generally much smaller. Calculated optical transitionmore »« less
Observation of slow dangling-bond relaxation in [ital p]-type hydrogenated amorphous silicon

Journal Article Carlen, M; Xu, Y; Crandall, R - Physical Review, B: Condensed Matter; (United States)

Using junction-capacitance methods, we study the thermal charge emission of holes trapped in the dangling-bond defect [ital D] of [ital p]-type [ital a]-Si:H. Over a significant temperature range, we find a linear temperature-independent relation between emission time and the residence time of the hole on the [ital D] defect. We attribute this characteristic to a structural-relaxation process that is slow in disordered materials.
https://doi.org/10.1103/PhysRevB.51.2173
Dangling-bond relaxation and deep-level measurements in hydrogenated amorphous silicon

Journal Article Branz, H; Schiff, E - Physical Review, B: Condensed Matter; (United States)

We present a new perspective on defect levels in hydrogenated amorphous silicon ([ital a]-Si:H) that unifies relaxation effects inferred from two recent experiments. In particular, we show how earlier calculations of dangling-bond relaxation can account for both the level deepening effect reported in transient capacitance measurements and the shallowing effect reported in transient photocurrent measurements under optical bias. The former is due to dangling-bond relaxation toward a pyramidal bonding configuration, and the latter to relaxation toward a planar configuration. We comment on the many-body nature of the remarkably slow kinetics of defect relaxation.
https://doi.org/10.1103/PhysRevB.48.8667
Dangling bonds in doped amorphous silicon: Equilibrium, relaxation, and transition energies

Journal Article Branz, H - Phys. Rev. B: Condens. Matter; (United States)

The phenomenology of the dangling-bond defect in doped hydrogenated amorphous silicon (a-Si:H) is analyzed in a thermodynamic equilibrium framework with use of positive correlation energy and defect relaxation energies taken from previous theoretical calculations. Good agreement is obtained between theoretical predictions and the optical absorption, luminescence, and deep-level transient spectroscopy energies from the experimental literature. Because the charge and hybridization of the dangling bond in doped a-Si:H are known, considerable information about dangling-bond energy levels and relaxations in a-Si:H is obtained. The controversy over an anomaly of about 0.9 eV in the sum of n-type and p-type films' optical-absorption-peak energiesmore »« less
https://doi.org/10.1103/PhysRevB.39.5107
Defect relaxation in amorphous silicon: Stretched exponentials, the Meyer-Neldel rule, and the Staebler-Wronski effect

Journal Article Crandall, R - Physical Review, B: Condensed Matter; (USA)

Annealing and production of metastable defects in disordered solids is explained quantitatively with a model in which defect relaxation is a local phenomenon. The stretched-exponential time dependence of defect relaxation and the Meyer-Neldel rule for the relaxation-time constant are natural consequences of this model. The results are obtained by using an exponential distribution of activation barriers for transitions between the two states of the local defect. The model, applied to data in hydrogenated amorphous silicon, {ital a}-Si:H, gives an exponential distribution of barriers with a characteristic temperature of 220 {degree}C, roughly equal to the accepted freeze-in temperature for defect distributionsmore »« less
https://doi.org/10.1103/PhysRevB.43.4057

Similar Records