Schottky diodes; indium phosphide; gaussian distribution; barrier height inhomogeneity; interface st
Department of Physics, Sri Venkateswara University, Tirupati 517 502, India
Adv. Mater. Lett., 2012, Current Issue, 3 (3), pp 188-196
Publication Date (Web): Jun 10, 2012
Copyright © IAAM-VBRI Press
We have investigated the temperature-dependent current-voltage (I-V) and capacitance-voltage (C-V) characteristics of Pd/V Schottky contacts on n-type InP in the temperature range of 200-400 K. The estimated barrier height for the Pd/V/n-type InP SBDs from the I-V and C-V characteristics have varied from 0.48 eV to 0.65 eV (I-V) and 0.85 eV to 0.69 eV (C-V), and the ideality factor (n) from 4.87 to 1.58 in the temperature range 200 to 400 K. It has been observed that the ideality factor decreases while the barrier height increases with increase of temperature. Such behaviour is attributed to barrier inhomogeneities by assuming a Gaussian distribution of barrier heights at the interface. Further, it is found that the series resistance (RS) values of Pd/V/n-InP Schottky diode estimated from Cheung’s function are strongly temperature dependent. The zero-bias barrier height ?bo versus 1/2kT plot has been drawn to obtain the evidence of a Gaussian distribution of the barrier height. The estimated value of ?bo is 0.89 eV with standard deviation σo=145 meV. The mean barrier height and the Richardson constant are determined by the modified Richardson plot ln(Io/T2)-(q2?2o/2k2T2) versus 1/T and are respectively 0.72 eV and 6.59 Acm-2K-2 respectively. Also, the discrepancy between the BHs obtained from the I-V and C-V characteristics is discussed. The interface state densities extracted for the Pd/V/n-InP Schottky diode are in the range of 5.14×1012 to 3.21×1012 eV-1cm-2 in the bandgap below conduction band form EC-0.25 to EC-0.51 eV.
Schottky diodes, indium phosphide,gaussian distribution, barrier height inhomogeneity, interface state density.