Bulk CVD diamond devices for UV and XUV detection

Abstract

Owing to its semiconducting properties (wide band gap, high electron and hole mobility), diamond is an interesting material for UV and XUV photodetection. In the present study, we have characterized UV and XUV diamond photodetector efficiency using bulk photoconductivity instead of usual coplanar devices. For comparisons, chemical vapor deposition diamond films of 200-μm thickness have been fabricated for working either in bulk configuration (BC) or surface configuration. They have been tested under nanosecond laser irradiation in the gap region (over-gap 193 and 213 nm; sub-gap 266 nm). For each wavelength, photoconductive responses of devices have been measured as a function of bias voltage (AC and DC) and laser fluences. With BC linear responses are obtained up to 0.5 mJ/cm 2 at 193 nm and 40 mJ/cm 2 at 266 nm. However, with BC a space charge effect appears under 193- and 213-nm irradiation, reducing the sensitivity of the detector. Such drawback is overcome by using AC bias. The suitability of the devices for detecting UV laser pulses or intense XUV fast discharge lamp is discussed.