Electrical characterization of an epitaxial ZnSe/epitaxial GaAs heterointerface

Abstract

The electrical properties of pseudomorphic epilayer–epilayer ZnSe/GaAs heterointerfaces, grown by molecular-beam epitaxy, have been investigated by capacitance versus voltage (C–V) and current versus voltage measurements. Undoped stoichiometric ZnSe (<1000 Å), exhibiting high resistivity, performs the function of the insulator in these metal–insulator–semiconductor capacitors. The C–V characteristics of the annealed Au/ZnSe/p-GaAs capacitors are nearly ideal, exhibiting an interface state density (2.5×1011 cm−2) which compares favorably with the densities reported at typical (Al,Ga)As interfaces. The occurrence of both hole accumulation (for p-type GaAs) and inversion (for n-type GaAs) at the ZnSe/GaAs heterointerface indicates the presence of a substantial valence-band offset. The lack of accumulation or inversion layers for electrons suggests a relatively small conduction-band discontinuity.