Photo-Hall measurements on phosphorus-doped n-type CVD diamond at low temperatures

Abstract

DC photo-conductivity and photo-Hall effect measurements were applied for the first time to measure electron transport properties of two 2-4 x 10(18) cm(-3) P-doped n-type diamonds at low temperatures down to 10 K. The low IR photosensitivity, sub-linear variation of free-electron concentration with IR light intensity as well as their freeze-out at very low temperatures were observed and explained by the presence of non-uniformly distributed defect-induced localized states (traps) in the band gap. Electron mobilities of the order of 400-500 cm(2)/Vs were measured at 10 K decreasing with increasing temperature as T-1/2 to about 150-200 cm(2)/Vs at 300 K, in contrast to T-3/2 law expected for ionized impurity scattering. Lattice distortions extending to several nm around P atoms are discussed as possible scattering centers. (C) 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.