Pseudovertical Schottky Diodes on Heteroepitaxially Grown Diamond

Abstract

Substrates comprising heteroepitaxially grown single-crystalline diamond epilayers were used to fabricate pseudovertical Schottky diodes. These consisted of Ti/Pt/Au contacts on p (Formula presented.) Boron-doped diamond (BDD) layers (10 (Formula presented.) –10 (Formula presented.) cm (Formula presented.)) with varying thicknesses countered by ohmic contacts on underlying p (Formula presented.) layers (10 (Formula presented.) –10 (Formula presented.) cm (Formula presented.)) on the quasi-intrinsic diamond starting substrate. Whereas the forward current exhibited a low-voltage shunt conductance and, for higher voltages, thermionic emission behavior with systematic dependence on the p (Formula presented.) film thickness, the reverse leakage current appeared to be space-charge-limited depending on the existence of local channels and thus local defects, and depending less on the thickness. For the Schottky barriers (Formula presented.), a systematic correlation to the ideality factors n was observed, with an “ideal” n = 1 Schottky barrier of (Formula presented.) = 1.43 eV. For the best diodes, the breakdown field reached 1.5 MV/cm.