Epitaxial graphene (EG)/SiC based Schottky emitter bipolar phototransistors for UV detection and effect of hydrogen intercalation on device I-V characteristics

Wideband gap semiconductor materials such as SiC and GaN are popular for UV detection applications. Also, epitaxial growth of graphene on SiC is suitable for the development of large area electronic and optoelectronic devices based on EG/SiC junctions. Epitaxial graphene(EG) grown on SiC forms a Schottky junction with highly asymmetric barrier for both electrons and holes. We have previously reported a high gain bipolar photo-transistor for UV detector applications. In this present study, we report the current-voltage (I-V) and gain characteristics of these devices before and after hydrogen intercalation process step. It is observed that the gain has decreased after intercalation which is possibly due to reduced minority carrier injection efficiency. Additionally, the device I-V characteristics are measured under sub bandgap blue laser excitation and from these results, the UV-Visible rejection ratio is estimated to be about 4500.