Dresden 2006 – scientific programme
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HL: Halbleiterphysik
HL 25: C/diamond
HL 25.1: Talk
Tuesday, March 28, 2006, 18:00–18:15, POT 151
Electronic and optical properties of boron-doped nanocrystalline diamond — •Wojciech Gajewski1, Jose Garrido1, Ken Haenen2, Oliver Williams2, and Martin Stutzmann1 — 1Walter Schottky Institute, - TU München, Am Coulombwall 3, 85748 Garching — 2Institute for Materials Research, University of Hasselt, Wetenschapspark 1, 3590, Belgium
We report the optical and electronic properties of boron-doped nanocrystalline diamond (B-NCD) thin films, grown on quartz substrates by CH4/H2 plasma CVD. Diamond thin films with a thickness below 200 nm and with boron concentractions rangeing from 0 to 5000 ppm have been investigated. Hall effect measurements confirmed the expected p-type conductivity. The conductivity of B-doped NCD samples with low boron concentrationin the gas phase strongly depends on temperature. The carrier concentration in the temperature range from 400K to 700K is thermally activated. At higher boron doping, the conductivity and the carrier concentration are no longer temperature dependent, and the samples exhibit quasimetallic properties. The Hall mobility shows no clear temperature dependence. As expected, the higher the carrier concentration, the lower the mobility. Spectrally resolved photocurrent measurements have revealed a strong dependence of the photosignal on the surface termination. Major differences occur in the energy range 3.5 - 5.4 eV. The influence of grain boundaries and surface states on the electronic transport and optical properties will be discussed.