Double barrier height nature of Ti/p-type strained Si-on-insulator schottky diode and its low frequency noise characteristics

The current-voltage (I-V) and capacitance-voltage (C-V) characteristics of a Ti/p-type strained Si-on-insulator (sSOI) Schottky diode were measured as a function of temperature in the range, 175-375 K. The Schottky barrier parameters of the Ti/p-type sSOI diode, which were interpreted using thermionic emission theory, indicated a strong temperature dependence of the barrier height and ideality factor. The barrier height and ideality factor decreased and increased, respectively, with decreasing temperature, which was attributed to the distribution of barrier heights due to the inhomogeneity at the metal-semiconductor interface. In addition, the discrepancy in the barrier heights obtained from the I-V and C-V techniques confirmed the inhomogeneities in the Schottky barrier. The inhomogeneities in the barrier characterized under the assumption of a Gaussian distribution revealed the existence of a double barrier distribution with a transition occurring at 275 K. The Richardson plot interpreted with the Gaussian distribution approach yielded a Richardson constant of 21.4 Acm^-2K^-2 in the high temperature region close to the theoretical value of 31.6 Acm^-2K^-2 for p-type sSOI. The low frequency noise measurements of the Ti/p-type sSOI Schottky diodes in the forward bias exhibited a 1/f^gamma; dependence with gamma; ranging from 0.67 to 1.30, indicating the origin of noise due to the fluctuations in the carrier number caused by trapping-detrapping processes in the traps of the depletion region. Furthermore, the current-noise-power spectral density indicated the presence of defect states or traps existing in the depletion region or in the forbidden gap of the sample.