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The Gaussian distribution of barrier height in Au/n-GaAs Schottky diodes at high temperatures

A. TATAROĞLU1,* , S ALTINDAL1, F. Z. PÜR1, T. ATASEVEN1, S SEZGIN1

Affiliation

  1. Physics Department, Faculty of Arts and Sciences, Gazi University, 06500, Teknikokullar, Ankara, Turkey

Abstract

The current-voltage (I-V) characteristics of Au/n-GaAs (MS) Schottky diodes were determined in the temperature range of 300-400 K. The estimated zero-bias barrier height (Bo) and the ideality factor (n) assuming thermionic emission (TE) theory show strong temperature dependence. The barrier height for current transport decreases and the ideality factor increases with the decrease temperatures. This behavior of Bo and n is attributed to Schottky barrier inhomogeneities by assuming a Gaussian distribution (GD) of the barrier heights (BHs) at the metal/semiconductor interface. The Richardson plot is found to be linear in the temperature range measured, but activation energy value of 0.322 eV and Richardson constant (A*) value f 4.12x10-4 Acm-2K-2obtained this plot are much lower than the known values. The nonlinearity in the Richardson plot and strong dependence of Schottky barrier parameters on temperature may be attributed to the spatial inhomogeneity in the interface. We attempted to draw a Bo versus q/2kT plot in order to obtain evidence of the GD of BHs, and the values of Bo  = 0.912 eV and o  = 0.132 V for the mean barrier height and standard deviation at a zero bias, respectively, were obtained from this plot. A modified ln(Io/T2)-q2o 2/2k2T2 versus q/kT plot gives Bo  and A* as 0.914 eV and 8.32 Acm-2K-2, respectively. This value of the Richardson constant 8.32 Acm-2K-2 is very close to the theoretical value of 8.16 Acm-2K-2 for n-type GaAs..

Keywords

MS Schottky diodes, Thermionic emission, Ideality factor, Barrier height, Gaussian distribution, Richardson constant.

Citation

A. TATAROĞLU, S ALTINDAL, F. Z. PÜR, T. ATASEVEN, S SEZGIN, The Gaussian distribution of barrier height in Au/n-GaAs Schottky diodes at high temperatures, Optoelectronics and Advanced Materials - Rapid Communications, 5, 4, April 2011, pp.438-442 (2011).

Submitted at: Sept. 15, 2010

Accepted at: April 11, 2011