Examination of tunnel junctions in the AlGaN/GaN system: Consequences of polarization charge

A strong piezoelectric effect and a large spontaneous polarization allow one to incorporate a large electric field (>106 V/cm)(>106V/cm) and high sheet charge (>1013 cm−2)(>1013cm−2) without doping in the AlGaN/GaN heterostructure. Theoretical studies are done to examine how polarization effects can be exploited to design metal–AlGaN/GaN tunnel junctions. We find that with a proper choice of AlGaN thickness undoped junctions can be made with very high metal to two-dimensional electron gas tunneling. Thus, a Schottky junction can be converted to a tunnel junction without doping. The tunneling probabilities approach those produced in a system doped at ∼ 4×1019 cm−3.∼4×1019cm−3. This work suggests that very interesting tunnel junctions can be made from undoped AlGaN/GaN heterostructures. © 2000 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/70932/2/APPLAB-77-12-1867-1.pd