All-epitaxial Al/AlGaN/GaN low-barrier Schottky diodes

All-epitaxial Al/AlxGa1-xN/GaN low-barrier Schottky diodes with different x compositions were fabricated in the single process of molecular-beam epitaxy. A decrease in the effective barrier height is achieved by polarization-induced delta-doping of the AlxGa1-xN/GaN heterojunction. At zero bias, the diodes have high values of ampere-watt sensitivity (7 A/W) with a low specific value of differential resistance (5 x 10(-4) omega.cm(2)) and retain non-linear properties when the resistance decreases to 10(-4) omega.cm(2). The fundamental importance of the absence of impurities, oxides, and structural defects at the metal-semiconductor interface for effective control of the transport properties of diodes is demonstrated.