Download or read book Research on the Structural and Electronic Properties of Defects in Amorphous Silicon written by R. A. Street and published by . This book was released on 1991 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Research on the Structural and Electronic Properties of Defects in Amorphous Silicon Final Subcontract Report September 1989 December 1990 written by and published by . This book was released on 1991 with total page 52 pages. Available in PDF, EPUB and Kindle. Book excerpt: The work performed for this contract focused on the saturation of light-induced effects, hydrogen-mediated metastability and growth, defects and electronic properties, and remote hydrogen plasma growth. This work included research on hydrogen chemical reactions, hydrogen density-of-states model and metastability, hydrogen bonding configurations, a model for the role of hydrogen complexes in the metastability, and hydrogen chemical potential and growth structure. This document also covers research on thermal generation currents in p-i-n diodes, field dependence of the generation current, metastability effects at contacts, and potential fluctuations in compensated a-Si:H. Information is included on plasma diagnostics using electron spin resonance and nuclear magnetic resonance measurements of remote hydrogen plasma films.
Download or read book Energy Research Abstracts written by and published by . This book was released on 1993 with total page 754 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Research on the Structural and Electronic Properties of Defects in Amorphous Silicon written by Xerox Corporation. Palo Alto Research Center and published by . This book was released on 1990 with total page 44 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Studies on Relative Effects of Charged and Neutral Defects in Hydrogenated Amorphous Silicon Final Report 1 October 1989 31 December 1990 written by and published by . This book was released on 1992 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report covers the third year of a continuing research study to understand the relative importance of charged and neutral defects in amorphous silicon. The objective of the study is to explore the electronic structure, including neutral and charged defects, an optoelectronic effects including the formation of Staebler-Wronski defects. The study concentrated on exploring electroluminescence experimentally and interpreting the results employing a simple guiding model. The simple guiding model assumes an exponential density of states and recombination rate constants (radiative and non-radiative) which are governed by hopping transitions. Measurements were also made as a function of photodegradation of the material. The results implicate that the radiative recombination processes are not distant pair tunneling but rather results from electrons hopping down due to the coulomb interactions. Preliminary experiments have been made on the effect of photodegradation on transient space charge limited currents in n/i/n structures. These experiments can directly yield information on the occupied defects centers induced by the photodegradation and are not a result of recombination processes. To date the results seems to be consistent with a picture which places the doubly occupied defects at quite a high energy ((asymptotically equal to) 0.4 e.v. below the conduction band).
Download or read book Research on the Structural and Electronic Properties of Defects in Amorphous Silicon written by and published by . This book was released on 1991 with total page 52 pages. Available in PDF, EPUB and Kindle. Book excerpt: The work performed for this contract focused on the saturation of light-induced effects, hydrogen-mediated metastability and growth, defects and electronic properties, and remote hydrogen plasma growth. This work included research on hydrogen chemical reactions, hydrogen density-of-states model and metastability, hydrogen bonding configurations, a model for the role of hydrogen complexes in the metastability, and hydrogen chemical potential and growth structure. This document also covers research on thermal generation currents in p-i-n diodes, field dependence of the generation current, metastability effects at contacts, and potential fluctuations in compensated a-Si:H. Information is included on plasma diagnostics using electron spin resonance and nuclear magnetic resonance measurements of remote hydrogen plasma films.
Download or read book Government Reports Annual Index written by and published by . This book was released on 1994 with total page 1104 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Government Reports Announcements Index written by and published by . This book was released on 1995 with total page 1126 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Fundamental Studies of Defect Generation in Amorphous Silicon Alloys Grown by Remote Plasma enhanced Chemical vapor Deposition Remote PECVD Annual Subcontract Report 1 September 1990 31 August 1991 written by and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We demonstrated that the remote PECVD process can be used to deposit heavily doped n-type and p-type a-Si:H thin films. We optimized conditions for depositing undoped, near-intrinsic and heavily doped thin films of [mu]c(microcrystalline)-Si by remote PECVD. We extended the remote PECVD process to the deposition of undoped and doped a-Si, C:H and [mu]c-Si, C alloy films. We analyzed transport data for the dark conductivity in undoped and doped a-Si:H, a-Si, C:H, [mu]c-Si and [mu]c-Si, C films. We studied the properties of doped a-Si:H and [mu]c-Si in MOS capacitors using [approximately]10 [Omega]-cm p-type crystalline substrates and thermally grown Si0[sub 2] dielectric layers. We collaborated with a group at RWTH in Aachen, Germany, and studied the contributions of process induced defect states to the recombination of photogenerated electron pairs. We applied a tight-binding model to Si-Bethe lattice structures to investigate the effects of bond angle, and dihedral angle disorder. We used ab initio and empirical calculations to study non-random bonding arrangements in a-Si, O:H and doped a-Si:H films.
Download or read book Research on Defects and Transport in Amorphous silicon based Semiconductors Final Subcontract Report 20 February 1991 19 April 1994 written by and published by . This book was released on 1994 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report describes work on three individual tasks as follows. (1) Electron and hole drift measurements in a-Si{sub 1-x}Gex:H and a-Si{sub 1-x}Cx:H p-i-n solar cells. Multijunction solar cells incorporating modified band gap a-Si:H in a triple-junction structure are generally viewed as the most promising avenue for achieving an amorphous silicon-based solar call with 15% stabilized conversion efficiency. The specific objective of this task was to document the mobilities and deep-trapping mobility-lifetime products for electrons and holes in a-Si{sub 1-x}Gex:H and a-Si{sub 1-x}Cx:H alloys materials. (2) Electroabsorption measurements and built-in potential (V{sub bi}) in solar cells. V{sub bi} in a p-i-n solar call may be limiting the open-circuit voltage (V{sub oc}) in wide-band-gap cells (E{sub g}> 1.8 eV) currently under investigation as the top cell for 15% triple junction devices. The research addressed four issues that need to be resolved before the method can yield an error less than 0.1 V for V{sub bi}. The details are presented in this report. (3) Defect relaxation and Shockley-Read kinetics in a-Si:H. Quantitative modeling of solar cells is usually based on Shockley-Read kinetics. ̀̀An important assumption of this approach is that the rate of emission of a photocarrier trapped on a defect is independent of quasi-Fermi level location.
Download or read book Research on Defects and Transport in Amorphous silicon based Semiconductors Annual Subcontract Report 20 February 1992 19 February 1993 written by and published by . This book was released on 1993 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report describes Phase 2 progress in two areas: (1) electron drift and conduction band tails in a-Si{sub 1-x}Ge(subscript x):H and a-Si{sub 1-x}C(subscript x):H alloys, and (2) optical bias effects on electron trapping and emission in a-Si:H. The authors completed a comprehensive study of electron drift in a-Si{sub 1-x}Ge(subscript x):H alloys, including correlations of the drift parameters with {open_quotes}blue{close_quotes} fill factor measurements and open-circuit voltages in solar cells. They began a study of electron and hole drift in a-Si{sub 1-x}C(subscript x):H, but, at present, they have only confirmed that C alloying degrades the electron drift mobility in a-Si{sub 1-x}C(subscript x):H. They completed a study of optical bias effects on transient photocharge measurements in a-Si:H, which clarified that optical bias effects found in earlier photocurrent transient measurements occur because deep trapping is suppressed by optical bias.
Download or read book Research on Defects and Transport in Amorphous Silicon based Semiconductors Annual Subcontract Report 20 February 1991 19 February 1992 written by and published by . This book was released on 1992 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report describes the results from research on two topics: (1) the effects of light-soaking on the electron drift mobility in a-Si:H, and (2) modulated electron spin resonance measurements and their relationship to the electronic correlation energy of the D center in a-Si:H. Both of these projects were undertaken to better determine where the ''standard'' model for a-Si:H breaks down. The standard model is reasonably successful in accounting for the most elementary ''deep trapping'' aspects of electron and hole transport in a-Si:H, and it accounts adequately for the sub-band-gap optical properties. However, it is much less clear whether it provides a sufficient basis for understanding several effects which are crucial in operating solar cells: electron and hole mobilities and recombination in the presence of light-bias and space-charge. In the standard model, one would not expect significant effects on drift mobilities due to light-soaking, which would be envisioned as simply increasing the D-center density. Similarly, in the standard model one would not anticipate a significant temperature dependence to electron spin resonance, because essentially all spins are already detected. Discussions in the available literature on the evidence regarding both effects were inconclusive. The work reported here sets considerably more stringent constraints on the magnitude of the two effects.
Download or read book Studies on Relative Effects of Charged and Neutral Defects in Hydrogenated Amorphous Silicon written by and published by . This book was released on 1992 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report covers the third year of a continuing research study to understand the relative importance of charged and neutral defects in amorphous silicon. The objective of the study is to explore the electronic structure, including neutral and charged defects, an optoelectronic effects including the formation of Staebler-Wronski defects. The study concentrated on exploring electroluminescence experimentally and interpreting the results employing a simple guiding model. The simple guiding model assumes an exponential density of states and recombination rate constants (radiative and non-radiative) which are governed by hopping transitions. Measurements were also made as a function of photodegradation of the material. The results implicate that the radiative recombination processes are not distant pair tunneling but rather results from electrons hopping down due to the coulomb interactions. Preliminary experiments have been made on the effect of photodegradation on transient space charge limited currents in n/i/n structures. These experiments can directly yield information on the occupied defects centers induced by the photodegradation and are not a result of recombination processes. To date the results seems to be consistent with a picture which places the doubly occupied defects at quite a high energy ({approx equal} 0.4 e.v. below the conduction band).
Download or read book Defect States in Plasma deposited A Si written by and published by . This book was released on 1980 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Studies of defects in plasma-deposited, hydrogenated amorphous silicon (a-Si:H), covering the period February 1979-January 1980 are described. Substantial progress has been made in understanding defect structures, their electronic properties and the influence of doping. The two most significant results are surprising, in one case for simplicity where complexity was expected, and in the other for complexity where simplicity had been presumed. In the first study we have clarified the nature of the defects by showing the connection between luminescence and light induced ESR experiments. The results indicate that dangling bonds having a positive electronic correlation energy are sufficient to explain most of the experimental information. The second study demonstrates the existence of microstructural inhomogeneities, arising from the nucleation and growth of the films. Thus the usual assumption of a uniform alloy with a random distribution of defects must be modified in considering processes such as electrical conduction, trapping, recombination, hydrogen effusion, etc. Of considerable technological and fundamental interest is the influence of doping on the defect behavior. Previous indications that doping introduces defect states have been confirmed. It remains to determine why this behavior occurs, and if there are any means of circumventing the problem.
Download or read book Research on Defects and Transport in Amorphous silicon based Semiconductors written by Eric A. Schiff and published by . This book was released on 1993 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Electronic Defects in Amorphous Silicon Materials and Devices written by Marc von der Linden and published by . This book was released on 1994 with total page 129 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Electronic Properties of Defects in Amorphous Semiconductors written by E. P. O'Reilly and published by . This book was released on 1981 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
