Impact ionization of excitons and shallow donors in InP

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Abstract
Quenching of neutral-donor- and exciton-related photoluminescence in high-purity liquid-phase-epitaxial and vapor-phase-epitaxial InP samples is studied as a function of applied weak electric fields at liquid-He temperatures. Field-dependent suppression of neutral-donor-to-acceptor and free- and bound-exciton recombination peaks in the spectrum is attributed to impact ionization of the shallow donors and excitons by hot electrons which were accelerated by the applied field. More rapid quenching of the neutral-donor-bound and neutral-acceptor-bound exciton peaks with increasing field strength as compared to neutral-donor and free-exciton peaks is attributed to the dissociation of free excitons from the neutral centers by impact ionization.