Akademik Veri Yönetim Sistemi
SEMICONDUCTOR SCIENCE AND TECHNOLOGY, cilt.19, sa.2, ss.270-276, 2004 (SCI-Expanded, Scopus)
In this study we have determined the density of states below the Fermi level in hydrogenated amorphous germanium thin films by different capacitance techniques. In order to realize the goal, a-Ge:H films were first deposited on c-Ge substrates and later they were converted into Cu/c-Ge/a-Ge:H/Al sandwich structures. The current-voltage and capacitance-voltage-frequency characteristics of the samples were measured at various temperatures. The forward current initially increased exponentially with an increase in the applied voltage up to 0.25 V and then continued to increase nonexponentially. It was found that the carrier transport mechanism in the exponential region is limited by tunnelling and the activation energy of the junction was obtained from this region to be 0.57 eV. The gap states below the Fermi level were determined by three different methods: differential capacitance-voltage method, drive-level capacitance method and capacitance-energy method. Defect densities of the order of 2 x 10(17) eV(-1) cm(-3) at just below the Fermi level have been obtained for our a-Ge:H samples.