Resonant acceptor levels in zero-gap semiconductors under uniaxial stress

Abstract

The variation with uniaxial stress of acceptor binding energy, as well as the natural level width, are calculated by the resolvent method in the case of zero-gap structures. We have neglected the warping of the ${\ensuremath{\Gamma}}_{8}$ bands and assumed a short-range impurity potential. When the resonant level merges into the induced gap and becomes a perfectly localized state, an anomaly appears in the stress dependence of the binding energy. A phase-shift analysis of the problem is presented, which enables a complete discussion of the nature of the impurity levels in zero-gap semiconductors.