Development of single-crystal CVD-diamond detectors for spectroscopy and timing

Charge-transport parameters measured for several single-crystal CVD-diamond films are discussed as well as the consequences for the energy- and the time resolution of charged-particle detectors made of these samples. Applying a transient-current technique, where Am-241 alpha-particles are used for e-h pair creation, low-field electron mobility values varying in the range 1300 < mu(0-e) [cm(2)/Vs] < 3100 are obtained, and a common saturation velocity around v(sat-e) approximate to 1.9 x 10(7) [cm/s]. Hole data show impressive uniformity with mu(0-h) approximate to 2330 [cm(2)/Vs] and v(sat-h) approximate to 1.4 x 10(7) [cm/s]. At detector operation bias (0.3 V/mu m < E-D < 3 V/mu m) the holes drift systematically faster than the electrons. The lifetime of the charge carriers in best samples amounts to tau(h) approximate to 1 mu s for holes and to tau(e) similar to 320 ns for electrons. Comparable to the energy resolution of commercial silicon detectors, a Delta E=17 keV (FWHM) is measured for 5.5 MeV alpha-particles and Delta E/E similar to 1% for heavy ions. Tests of single- and polycrystalline detectors with relativistic Al-27 ions of 2 AGeV reveal the same intrinsic time resolution of sigma(Delta t) = 28 ps indicating limitations due to electronic noise. (c) 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.