OPTICAL CHARACTERIZATION OF GAN SIC N-P HETEROJUNCTIONS AND P-SIC/

Optical characterization of GaN/SiC heterojunctions and p-SiC has been performed to explain the current-voltage (I-V) characteristics in GaN /SiC n-p heterojunction diodes. The I-V characteristics exhibit tunnel ing-assisted current with low forward ''turn-on'' voltages around 1.15 V as opposed to the expected drift/diffusion current with a turn on a round 2.5 V. Electroluminescence (EL) measurements on these diodes rev ealed an infrared peak at 1.25 eV and a red peak at 1.75 eV. Photolumi nescence (PL) measurements on p-SiC yielded peaks at 1.25 and 1.80 eV. Since the band gap of BH-SC is 3.03 eV, we attribute the EL and PL pe aks to radiative transitions from the conduction band edge to a defect level and subsequently down to the valence band edge of p-SiC. This d efect level is located 1.25 eV above the valence band edge. (C) 1998 A merican Institute of Physics.