Vertical and lateral GaN rectifiers on free-standing GaN substrates

Edge-terminated Schottky rectifiers fabricated on quasibulk GaN substrates showed a strong dependence of reverse breakdown voltage V-B on contact dimension and on rectifier geometry (lateral versus vertical). For small diameter (75 mum) Schottky contacts, V-B measured in the vertical geometry was similar to 700 V, with an on-state resistance (R-ON) of 3 m Omega cm(2), producing a figure-of-merit V-B(2)/R-ON of 162.8 MW cm(-2). Measured in the lateral geometry, these same rectifiers had V-B of similar to 250 V, R-ON of 1.7 m Omega cm(2) and figure-of-merit 36.5 MW cm(-2). The forward turn-on voltage (V-F) was similar to1.8 V (defined at a current density of 100 A cm(-2)), producing V-B/V-F ratios of 139-389. In very large diameter (similar to5 mm) rectifiers, V-B dropped to similar to6 V, but forward currents up to 500 mA were obtained in dc measurements. (C) 2001 American Institute of Physics.