II-VI/III-V heterointerfaces: Epilayer-on-epilayer structures

The integration of several optoelectronic device functions onto a common substrate material is an area which is currently being actively pursued. In an effort to achieve this objective, experiments are under way to examine the epitaxial growth and material properties of a variety of both II-VI and III-V compounds grown on a substrate where the II-VI/III-V heterostructure can be utilized. This paper describes some recent developments involving the molecular beam epitaxial (MBE) growth and characterization of two important II-VI/III-V heterostructures, CdTe/InSb and ZnSe/GaAs. The structures are formed taking three approaches, by using (i) surface passivation techniques, combined with transfer in air from one chamber to the other, (ii) separate growth chambers connected by an ultrahigh vacuum transfer module, and (iii) both III-V and II-VI growth is performed in the same growth chamber. Multiple quantum wells of InSb have been grown at low temperatures of 300°C, using either Sb₄ or Sb₂ (the Sb₂ originates from an antimony cracker). Electrical characterization of metal/pseudomorphic ZnSe/p-GaAs capacitor structures illustrates accumulation, depletion and deep depletion; high frequency capacitance versus voltage data indicate interface state densities for the ZnSe/GaAs interface to be comparable to those reported for (Al,Ga)As/GaAs interfaces. The following paper represents a combined summary of two papers presented at the 5th International Conference on Molecular Beam Epitaxy.