High-voltage single-crystal diamond diodes

Demonstration of a 2.5-kV diamond diode is provided by electrical measurements using a circular gold Schottky contact, with an area >1 mm², on large area freestanding single-crystal diamond consisting of a thin high purity layer (<1×10¹³ [B]/cm³) on a thicker heavily boron-doped (>1×0¹⁹ [B]/cm³) 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±400 cm²/Vs at room temperature. For temperatures between 300 K-32/ 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.