Acceptor activation energies in epitaxial CuGaSe2 grown by MOVPE

Epitaxial CuCaSe2 layers were grown on GaAs (100) by MOVPE. Net carrier concentration and resistivity were examined with respect to temperature using a Van-der-Pauw geometry Hall setup. Net carrier concentrations from 2 x 10(14) cm(-3) to 7 x 10(16)cm(-3) at room temperature were found with strong correlation to composition. All gallium-rich samples show high compensation cm near 1. Hole activation energies of approximately 80 and 110 meV were determined. Mobilities up to 400 cm(2)/Vs at room temperature and 1450 cm(2)/Vs at 100 K are determined confirming high material quality. We found temperature exponents for the mobility between - 1.53 and -2.03 indicating acoustic phonon scattering to be the dominant mechanism over the whole measurable temperature range, with one exception: one sample of minor copper excess shows an exponent of 1.33 at low temperature indicating ionized impurity scattering. (C) 2001 Elsevier Science B.V. All rights reserved.