Electrical Transport Characteristics of Pd/V/N-InP Schottky Diode From I-V-T and C-V-T Measurements

Authors S. Sankar Naik, V. Rajagopal Reddy
Department of Physics, Sri Venkateswara University, Tirupati-517502, India
Е-mail shankarnaik.phd@gmail.com
Issue Volume 3, Year 2011, Number 1, Part 5
Dates Received 04 February 2011, in final form 30 November 2011, published online 08 December 2011
Citation S. Sankar Naik, V. Rajagopal Reddy, J. Nano- Electron. Phys. 3 No1, 1048 (2011)
PACS Number(s) 73.30. + y, 73.40.Ei
Keywords Pd/V Schottky contacts, n-type InP, Temperature dependent I-V and C-V measurements, Gaussian distribution; barrier inhomogeneity.
The temperature dependence of current-voltage (I-V) and capacitance-voltage (C-V) characteristics of the Pd/V contacts on undoped n-type InP Schottky barrier diodes (SBDs) have been systematically investigated in the temperature range of 200-400 K. The transition metal palladium (Pd) is used as a second contact layer because it has high work function, it reacts with InP at low temperatures and improved contact morphology. The ideality factor (n) and zero-bias barrier height are found to be strongly temperature dependent and while the zero-bias barrier height Φbo (I-V) increases, the ideality factor n decreases with increasing temperature. The experimental values of BH and n for the devices are calculated as 0.48 eV (I-V), 0.85 eV (C-V) and 4.87 at 200 K, 0.65 eV (I-V), 0.69 (C-V) eV and 1.58 at 400 K respectively. The I-V characteristics are analyzed on the basis of thermionic emission (TE) theory and the assumption of Gaussian distribution of barrier heights due to barrier inhomogeneities that prevail at the metal-semiconductor interface. The zero-bias barrier height Φbo versus 1/2kT plot has been drawn to obtain the evidence of a Gaussian distribution of the heights and the values of φ=0.89 eV and σ0= 145 meV for the mean barrier height and standard deviation. The conventional Richardson plot exhibits non-linearity with activation energy of 0.53 eV and the Richardson constant value of 4.25 × 10– 6 Acm– 2 K– 2. From the C-V characteristics, measured at 1 MHz the capacitance was determined to increase with increasing temperature. C-V measurements have resulted in higher barrier heights than those obtained from I-V measurements. As a result, it can be concluded that the temperature dependent characteristic parameters for Pd/V/n-InP SBDs can be successfully explained on the basis of TE mechanism with Gaussian distribution of the barrier heights.

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