High-speed diamond photoconductors: a solution for high rep-rate deep-UV laser applications

Beam monitoring of excimer lasers operating at high powers in the deep ultra-violet (DUV) is becoming increasingly important, due to the rapid proliferation of these systems in micromachining, photolithography, and other areas of industrial interest. This task requires radiation-hard detectors able to operate effectively for extended periods at high laser rep-rates. DUV-visible-blind photoconductors can be fabricated on polycrystalline CVD diamond, a material that is intrinsically radiation-hard and visible-blind. However, the performance of detectors fabricated on as-grown material is insufficient to meet the requirements of many excimer laser applications. In this paper, we show that sequentially applied post-growth treatments can progressively change both the gain and speed of these devices. Charge-sensitive deep-level transient spectroscopy (Q-DLTS) and transient photoconductivity (TPC) has been used to study the effect of these treatments on the defect structure of our thin-film diamond detector material, For the first time, we report the successful operation of a diamond photoconductive device with linear bias and fluence-response characteristics at more than 1 kHz at 193 nm. (C) 2001 Elsevier Science B.V. All rights reserved.