Electrical Transport Studies of the Hydrogen-Related Compensating Donor in B-Doped Silicon Diodes
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ELECTRICAL TRANSPORT STUDIES OF THE HYDROGEN-RELATED COMPENSATING DONOR IN B-DOPED SILICON DIODES A. J. TAVENDALE*, A.A. WILLIAMS*, D. ALEXIEV* AND S.J. PEARTON** *Australian Atomic Energy Commission, Lucas Heights Research Laboratories PMB, Sutherland, NSW 2232, Australia **AT&T Bell Laboratories, Murray Hill, New Jersey 07974, USA ABSTRACT Transport of the hydrogen-related, acceptor-compensating defect has been observed in reverse-bias annealed Al-gate Schottky and n+-P diodes from hydrogenated, B-doped p-Si. Secondary ion mass spectroscopy (SIMS) profiling (deuterium substitution) confirmed field-aided migration. Significant differences in field transport (and thermal diffusion) between diodes from Hand D-treated p-Si(B) qualitatively indicates a monatomic species. The effect is interpreted as field drift of a positively charged species, possibly H+, with a donor charge state in the upper-half band gap, in conflict with long-held theory predicting very deep level activity. Acceptor compensation is unstable under minority (electron) carrier injection by forward bias or illumination at 25°C, supporting the acceptor-protonic trap pair model (A-H+) of Sah, Pan and Hsu [J. Appl. Phys. 57, 5148 (1985)]. INTRODUCTION The electrical compensation or neutralization of the shallow-level acceptor impurities B, Al, Ga and In in crystalline p-type Si exposed to monatomic hydrogen has been well demonstrated [1-3]. Sah et al. [4] had earlier inferred the role of hydrogen in studies of bulk acceptor neutralization in metal-oxide-semiconductor (p-Si) capacitors, the oxides of which were subjected to low energy electron irradiation or electron avalanche injection. Water-related species in the oxide layer were considered to be the source of hydrogen. Hydrogen involvement in the neutralization of acceptors has been confirmed chemically by SIMS of deuterium using isotopic substitution [5, 6]. The various bonding models responsible for neutralization have been reviewed by Johnson [7]. We have recently reported the apparent electro-transport of the hydrogen-related, bulk-compensating defect (H-BCD) in the depletion layers of reverse biased Schottky and n+-p junction diodes [8], interpreting this phenomenon in terms of field drift of a positively charged species, possibly H+. This conflicts with early theoretical predictions for very deep donor level activity for hydrogen in Si. Johnson [9] has also studied the field dependence of neutralization in biased n+-p diodes during hydrogenation, suggesting that diffusion of HO is responsible for transport. However, the possibility of H+ as the migrating species has again been raised by Pankove et al. [10] in a study of the role of holes in the injection of hydrogen into Si. In this paper we present results from additional studies of electric field and minority carrier effects in diodes from hydrogenated p-Si(B), coupled with SIMS (deuterium) chemical analyses, which are further evidence for the existence of a mobile H+ species. EXPERIMENTAL AND RESULTS The p-type, boron-doped Si used in this w
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