Time-resolved cyclotron resonance on dislocation-free HPHT diamond

Intrinsic transport properties in diamond are remained frontiers in material research of semiconductors. Here, we apply the time-resolved cyclotron resonance (TRCR) method to dislocation-free HPHT diamonds in order to elucidate the momentum relaxation mechanisms of photoexcited carriers. Two specimens of single sector crystals oriented along [001] and [111] directions are examined. The both specimens show clear TRCR signals below 40 K, where the signals in the (111)-oriented diamond decay faster than those in the (001)-oriented one. From the temperature dependence of the CR spectrum in the (111)-oriented diamond, carrier momentum relaxation rates at the low temperature limit are extracted. The rates are two/four times larger for heavy/light holes in the HPHT diamond than the previous results obtained in a high-purity CVD diamond, and include temperature-independent scattering by neutral impurities. We also deduce that the TRCR detection is rather insensitive to crystalline dislocations by considering the cyclotron radii of carriers.