Abstract

Photoconductivity measurements were used to get carrier lifetimes and mobilities in three forms of diamond: (i) natural type IIa diamond, (ii) synthetic high-pressure, high-temperature bulk diamond, and (iii) plasma enhanced chemical vapor deposited polycrystalline diamond film. Signals were generated by picosecond ultraviolet laser pulses. We find that the lifetimes of carriers generated in both the thin film and the type IIa diamonds are in the range of 100 to 600 ps, varying from sample to sample. In the thin film material, a much longer lifetime component is also observed on some samples and is attributed to the diamond-like carbon transition layer found in these samples. The data also suggests a grain size dependence in the lifetimes. In the synthetic bulk diamond, there was no fast component and the lifetimes were on the order of 4 ns. Mobilities in the thin film and type IIa were also comparable (around 10 to several hundred cm²/V-s), while in the synthetic bulk material, mobilities were around 30 cm²/V-s.

© 1989 Optical Society of America