Gaussian distribution of inhomogeneous barrier height in Al0.24Ga0.76As/GaAs structures

Current-voltage (I-V) characteristics of Al0.24Ga0.76As/GaAs structures have been investigated in the temperature range of 79-400 K. The barrier height Phi(B), ideality factor n and density of interface states N-ss determined from the forward bias I-V characteristics were found strongly depend on temperature. While the n and N-ss decrease, the zero-bias barrier height Phi(B0) increases with increasing temperature. This behavior has been interpreted by the assumption of a Gaussian distribution (GD) of barrier heights (BHs) due to the barrier inhomogeneities that prevail at the metal-semiconductor interface. A Phi(B0) versus q/2kT plot was drawn to obtain evidence of GD of BH, and values of (Phi(B0) = 0.788 eV and sigma(0) = 0.091 V for the mean BH and zero-bias standard deviation have been obtained from this plot, respectively. Furthermore, the mean values of BH (Phi(B0) and the effective Richardson constant A* were obtained as 0.804eV and 15.8 A/cm(2) K (2), which is close to the theoretical value of 8 A/cm(2) K-2, respectively, by means of the modified Richardson plot, ln(I-0/T-2)-q(2)sigma(2)(0)/2(kT)(2) versus q/kT plot. Experimental results show that Al 0.24Ga0.76As/GaAs structures have a good rectifying behavior and the temperature dependence of forward bias I-V characteristics of the Schottky barrier diode (SBD) have been successfully explained based on TE theory with GD of BHs. In addition, the N-ss was determined from the forward bias I-V characteristics by taking into account the bias dependence of the effective BH.(c) 2007 Elsevier B.V. All rights reserved.