SCANNING-TUNNELING-MICROSCOPY OF PASSIVATED GALLIUM-ARSENIDE UNDER AMBIENT CONDITIONS

Scanning tunnel spectroscopy of n- and p-type GaAs (110) and (100) surfaces, prepared with a novel electrically transparent surface oxide, reveals that the current-voltage (I-V) characteristics of these surfaces obtained in air exhibit transport properties typical of the bulk band structure, a result which was previously obtained only on (110) GaAs surfaces cleaved in ultrahigh vacuum. The passivation technique has been used to obtain stable images of cleaved, molecular-beam epitaxy grown GaAs pn junctions in air as well. The results of this study demonstrate that quantitative doping information over the range of 10(15) < N(A),N(D) < 10(19) cm-3 can be extracted from scanning tunneling microscopy data on passivated GaAs surfaces under ambient conditions.