Acceptorlike behavior of nitrogen deep traps inGaAs:N

Abstract

We report the observation of excited states of holes for acceptorlike excitons bound to isolated nitrogen impurities in $\mathrm{GaAs}:\mathrm{N}$ under high hydrostatic pressures. Appearance of a large absorption resonance $(5\phantom{\rule{0.3em}{0ex}}\mathrm{K})$ in optical transmission and photoluminescence excitation spectroscopies leads to the identification of the $2S$ excited hole state associated with the ground-state nitrogen isoelectronic bound exciton---commonly known as the ${\mathrm{N}}_{X}$ state from earlier $\mathrm{GaAs}$-based alloy studies. Comparison with the well-established effective-mass theory of Baldereschi and Lipari for excited-state $S$-type spectra of acceptors in semiconductors provides good qualitative agreement with our data. We thus deduce at $26.9\phantom{\rule{0.3em}{0ex}}\mathrm{kbar}$ the ground-state hole ionization energy as being $\ensuremath{\sim}19.2\phantom{\rule{0.3em}{0ex}}\mathrm{meV}$, which in turn leads to a unique electron binding energy of $\ensuremath{\sim}10.3\phantom{\rule{0.3em}{0ex}}\mathrm{meV}$ for isolated nitrogen traps in $\mathrm{GaAs}:\mathrm{N}$ at this pressure. These data and accompanying interpretations may provide for further understanding of the deep-level behavior of isoelectronic binding mechanisms in semiconductors.