Effect of charge manipulation on scanning tunneling spectra of single Mn acceptors in InAs

We present scanning tunneling spectroscopy measurements on Mn-doped InAs at low temperatures. In the range of conduction band tunneling, we observe a ring of increased differential conductance around each individual Mn acceptor. With increasing bias voltage, the ring shrinks and finally collapses. When the ring crosses the acceptor, the well known asymmetric feature of the bound-hole wave function appears in topographs. The behavior is explained by the tip-induced decharging of the Mn, which influences the spectra outside the extension of the wave function. Using a simple model, we show that the ring shape is given by the equipotential lines of the tip-induced quantum dot, while its intensity allows us to measure the screened potential of the charged acceptor.