High-voltage single-crystal diamond diodes

Abstract

Demonstration of a 2.5-kV diamond diode is provided by electrical measurements using a circular gold Schottky contact, with an area >1 mm/sup 2/, on large area freestanding single-crystal diamond consisting of a thin high purity layer (<1/spl times/10/sup 13/ [B]/cm/sup 3/) on a thicker heavily boron-doped (>1/spl times/0/sup 19/ [B]/cm/sup 3/) substrate with an ohmic back contact. The diode structures were fabricated using a microwave-assisted chemical vapor deposition process. The forward properties of the diode show a space charge limited current, with a forward-voltage drop of 2 V and a hole mobility of 4100/spl plusmn/400 cm/sup 2//Vs at room temperature. For temperatures between 300 K<T<380 K the mobility show T/sup -3/2/ dependence. This is consistent with acoustic phonon scattering, emphasizing the high purity quality of the top layer in which carrier transport is phonon rather than defect limited.