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[sub B] on contact dimension and on rectifier geometry (lateral versus vertical). For small diameter (75 μm) Schottky contacts, V[sub B] measured in the vertical geometry was ∼700 V, with an on-state resistance (R[sub ON]) of 3 mΩ cm2, producing a figure-of-merit V[sub B][sup 2]/R[sub ON] of 162.8 MW cm-2. Measured in the lateral geometry, these same rectifiers had V[sub B] of ∼250 V, R[sub ON] of 1.7 mΩ cm2 and figure-of-merit 36.5 MW cm-2. The forward turn-on voltage (V[sub F]) was ∼1.8 V (defined at a current density of 100 A cm-2), producing V[sub B]/V[sub F] ratios of 139–389. In very large diameter (∼5 mm) rectifiers, V[sub B] dropped to ∼6 V, but forward currents up to 500 mA were obtained in dc measurements. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]