Bipolar conduction across a wafer bonded p-n Si/SiC heterojunction

This paper describes the physical and electrical properties of a p-n Si/on-axis SiC vertical heterojunction rectifier. A thin 400nm p-type silicon layer was wafer-bonded to a commercial on-axis SiC substrate by room temperature hydrophilic wafer bonding. Transmission electron microscopy was used to identify the crystallographic orientation as (0001)SiC//(001)Si and to reveal an amorphous interfacial layer. Electrical tests performed on the p-n heterodiodes revealed that, after an additional 1000oC anneal, the rectifier exhibit remarkably low leakage current (10nA/cm2 at an anode voltage of V=-6V), improved on-resistance due to bipolar injection and a turn-on voltage close to the p-n heterojunction theoretical value of 2.4V.