Electrical and optical properties of p-SiC/n-GaN heterostructures

We report on the optical. electrical and structural properties of GaN films heteroepitaxially grown by low pressure chemical vapor deposition on 6H-SiC substrates. We employed photoluminescence (PL), Hall effect measurements, scanning tunneling microscopy (STM) and X-ray analysis to determine the quality of our films. Heterojunction diodes were Fabricated on p-type SiC and characterized by temperature dependent current-voltage and capacitance-voltage techniques. The results are interpreted within the thermionic emission model and the barrier found is attributed to the conduction band offset between 6H-SiC and wurtzite GaN. The diodes show electroluminescence of the donor-acceptor pair recombination type of 6H-SiC at room temperature. By analysis of the injection behavior pie can interpret our data, determining the high valence band offset between 6H-SiC and alpha-GaN to 0.67 eV. This high valence band offset favors applications for hetero-bipolar transistors (HBT). (C) 1997 Elsevier Science S.A.