Abstract

Application of polycrystalline diamond films in laser optics and electronics calls for detailed knowledge on mechanisms of their photoexcitation. As was recently reported, an exposure of the chemical vapour deposited (CVD) diamond films to UV radiation can enhance conductivity and photosensitivity in wide range of spectrum¹. To measure photoexcitation spectra in CVD and natural diamond and to reveal spectral details of the UV enhancement we combined registration of transient photoconductivity (TPC) with OPO as a source of short (~1 ns) pulses of intense radiation tuneable in the range 430-690 nm. TPC is a new “electrode-tree” technique, allowing to study mechanisms of absorption, behaviour of free electrons and holes and recombination with sub-nanosecond resolution time². The OPO applied was temperature tuneable travelling wave double pass oscillator-amplifier (ADP crystal), pumped by fourth harmonics of radiation of single frequency YAG:Nd laser. The samples were a high quality gem stone and a free standing diamond film grown by microwave plasma deposition technique.

© 1998 IEEE