FORMATION OF A THIN III-VI COMPOUND INTERFACIAL LAYER AT ZNTE ZNSE HETEROJUNCTION AND ITS EFFECT ON ENERGY-BAND DISCONTINUITY/

Interfacial layers were inserted at the interface of ZnSe and ZnTe in order to reduce both (1) the effect of strain and (2) the valence band discontinuity. The interfacial layer adapted in this study is the III -VI compound (Ga,Se). The layered structure GaSe is favorable for the present work, because it can be a buffer layer to relax the lattice mi smatch at the interface. All layers including ZnTe, (Ga,Se) and ZnSe w ere grown on (100) GaAs substrate by conventional molecular beam epita xy. The crystal structure of the (Ga,Se) on ZnSe was investigated. The growth of the layered structure GaSe layer on (100) ZnSe was very dif ficult, though the defect zinc-blende structure Ga2Se3 layer could be easily grown. The defect zinc-blende structure Ga2Se3 was inserted at the interface of ZnSe and ZnTe so that the valence band discontinuity could be modified. The discontinuity was decreased to about 0.1 eV whe n the thickness of the interfacial layer was about 8 Angstrom. The cur rent-voltage characteristics were measured for the sample with Ga2Se3 interfacial layer. The structure with Ga2Se3 exhibited the ohmic prope rty. These results suggest that the valence band discontinuity between ZnTe and ZnSe can be reduced by introducing the Ga2Se3 interfacial la yer.