EX-SITU FORMATION OF HGSE ELECTRICAL CONTACTS TO P-ZNSE

A novel method of forming semimetal HgSe electrical contacts to p-type ZnSe through an ex situ growth process has been developed. The ex sit u process consisted of deposition of an amorphous Se capping layer on p-ZnSe prior to removal from the molecular beam epitaxy (MBE) growth c hamber. This capping layer protected the p-ZnSe from contamination and oxidation upon removal from the MBE growth chamber. This capping laye r was reacted with Hg to form HgSe by heating to 150 degrees C for sim ilar to 15 min in Hg vapor. Transmission electron microscopy and x-ray diffraction data showed that the cubic HgSe phase was formed. Auger s putter depth profiling data were consistent with the formation of stoi chiometric HgSe. The electrical characteristics of the contacts were s tudied using temperature dependent I-V measurements which showed that thermionic emission dominated conduction across the interface for low reverse biases (V-R<2.5 V). However, thermionic field emission dominat ed conduction for V-R>2.5 V. The barrier height for thermionic emissio n and the energy parameter for tunneling were determined to be similar to 0.55 and 0.0076 eV, respectively, consistent with an unpinned Ferm i level. (C) 1996 American Vacuum Society.