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Title: Surface Passivation Optimization Using DIRECT

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Publication Date:
Research Org.:
National Renewable Energy Lab. (NREL), Golden, CO (United States)
Sponsoring Org.:
OSTI Identifier:
DOE Contract Number:
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Computational Physics; Journal Volume: 224; Journal Issue: 2, 2007
Country of Publication:
United States

Citation Formats

Graf, P. A., Kim, K., Jones, W. B., and Wang, L. W.. Surface Passivation Optimization Using DIRECT. United States: N. p., 2007. Web. doi:10.1016/
Graf, P. A., Kim, K., Jones, W. B., & Wang, L. W.. Surface Passivation Optimization Using DIRECT. United States. doi:10.1016/
Graf, P. A., Kim, K., Jones, W. B., and Wang, L. W.. Mon . "Surface Passivation Optimization Using DIRECT". United States. doi:10.1016/
title = {Surface Passivation Optimization Using DIRECT},
author = {Graf, P. A. and Kim, K. and Jones, W. B. and Wang, L. W.},
abstractNote = {},
doi = {10.1016/},
journal = {Journal of Computational Physics},
number = 2, 2007,
volume = 224,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
  • We describe a systematic and efficient method of determining pseudo-atom positions and potentials for use in nanostructure calculations based on bulk empirical pseudopotentials (EPMs). Given a bulk EPM for binary semiconductor X, we produce parameters for pseudo-atoms necessary to passivate a nanostructure of X in preparation for quantum mechanical electronic structure calculations. These passivants are based on the quality of the wave functions of a set of small test structures that include the passivants. Our method is based on the global optimization method DIRECT. It enables and/or streamlines surface passivation for empirical pseudopotential calculations.
  • Textured silicon surfaces are widely used in manufacturing of solar cells due to increasing the light absorption probability and also the antireflection properties. However, these Si surfaces have a high density of surface defects that need to be passivated. In this study, the effect of the microscopic surface texture on the plasma surface passivation of solar cells is investigated. The movement of 10{sup 5} H{sup +} ions in the texture-modified plasma sheath is studied by Monte Carlo numerical simulation. The hydrogen ions are driven by the combined electric field of the plasma sheath and the textured surface. The ion dynamicsmore » is simulated, and the relative ion distribution over the textured substrate is presented. This distribution can be used to interpret the quality of the Si dangling bonds saturation and consequently, the direct plasma surface passivation.« less
  • Al{sub 2}O{sub 3} was deposited on In{sub 0.15}Ga{sub 0.85}As/GaAs using atomic-layer deposition (ALD). Without any surface preparation or postthermal treatment, excellent electrical properties of Al{sub 2}O{sub 3}/InGaAs/GaAs heterostructures were obtained, in terms of low electrical leakage current density (10{sup -8} to 10{sup -9} A/cm{sup 2}) and low interfacial density of states (D{sub it}) in the range of 10{sup 12} cm{sup -2} eV{sup -1}. The interfacial reaction and structural properties studied by high-resolution x-ray photoelectron spectroscopy (HRXPS) and high-resolution transmission electron microscopy (HRTEM). The depth profile of HRXPS, using synchrotron radiation beam and low-energy Ar{sup +} sputtering, exhibited no residual arsenicmore » oxides at interface. The removal of the arsenic oxides from Al{sub 2}O{sub 3}/InGaAs heterostructures during the ALD process ensures the Fermi-level unpinning, which was observed in the capacitance-voltage measurements. The HRTEM shows sharp transition from amorphous oxide to single crystalline semiconductor.« less
  • The structure of hydrogenated silicon (Si:H) films deposited by rf and dc plasma process on Si (100) and (111) wafers is correlated with the surface passivation quality and heterojunction cell performance. Microstructural defects associated with SiH{sub 2} bonding and apparent ion bombardment in dc plasmas have little or no adverse effect on passivation or cell properties, while presence of crystallinity in Si:H i layer severely deteriorates surface passivation and cell open circuit voltage (V{sub oc}). Excellent surface passivation (lifetime of >1 ms) and high efficiency cells (>18%) with V{sub oc} of 694 mV are demonstrated on n-type textured Czochralski wafermore » using dc plasma process.« less