CALCULATION OF VALENCE-BAND OFFSETS OF LATTICE-MATCHED GAINTIP INP HETEROSTRUCTURES AND OF SCHOTTKY-BARRIER HEIGHTS OF METAL-GAINTIP CONTACTS/

Quaternary Ga0.18(1-y)InyTl0.82(1-y)P alloys are lattice matched with InP and their band gaps were predicted to be direct and to vary from z ero width to 1.35 eV, the value of InP. This study calculates the bran ch points of the interface-induced gap states of the binary compound T lP and of the ternary GaTlP and InTlP as well as some quaternary GaInT lP alloys using an empirical tight-binding approach. Several predictio ns are made. First, the band lineup of lattice-matched InP/Ga0.18(1-y) InyTl0.82(1-y)P heterostructures is of type I. Second, the conduction- band discontinuities are larger than the valence-band offsets. And thi rd, metal/Ga0.18(1-y)InyTl0.82(1-y)P contacts are naturally ohmic for indium contents y smaller than approximately 0.5. (C) 1997 American In stitute of Physics.