Characteristics of microwave photoconductivity of natural diamond in the spectral range 200-250 nm

Mechanically polished plates of natural diamond of the IIa and Ia types wer e investigated by the microwave photoconductivity (MW PC), conventional (di rect-current or, more precisely, low-frequency) photoconductivity (LF PC), and optical-absorption techniques. It is shown that the polycrystalline str ucture of the samples and high spatial inhomogeneity of the impurity defect distribution provide differences in MW PC and LF PC spectra. It is assumed that nonequilibrium holes in the illuminated diamond are trapped by the cr ystallite boundaries, while free electrons "oscillate" within the crystalli tes during their lifetime. The influence of chemical and mechanical treatme nt on the LF and MW PC is demonstrated. (C) 2000 MAIK "Nauka/Interperiodica ".