Temperature-dependent optical absorption measurements and Schottky contact behavior in layered semiconductor n-type InSe(:Sn)

The layered n-InSe(:Sn) single crystal samples have been cleaved from a large crystal ingot grown from non-stoichiometric melt by the Bridgman-Stockbarger method. It has been made the absorption measurements of these samples without Schottky contact under electric fields of 0.0 and 6000 V cm(-1). The band gap energy value of the InSe:Sn has been calculated as 1.36 +/- 0.01 eV (at 10 K) and 1.28 +/- 0.01 eV (at 300 K) tinder zero electrical held, and 1.31 +/- 0.01 eV (at 10 K) and 1.26 +/- 0.01 eV (at 300 K) under 6000 V cm(-1). The current-voltage (I-V) characteristics of Au-Ge/InSe(:Sn)/In Schottky diodes have been measured in the temperature range 80-320 K with a temperature step of 20 K. An experimental barrier height (BH)Phi(ap) value of about 0.70 +/- 0.01 eV was obtained for the Au-Ge/InSe(:Sn)/In Schottky diode at the room temperature (300 K). An abnormal decrease in the experimental BH Phi(b) and an increase in the ideality factor n with a decrease in temperature have been explained by the barrier inhomogeneities at the metal-semiconductor interface. From the temperature-dependent I-V characteristics of the Au-Ge/InSe(:Sn)/In contact, that is, Phi(bo) and A* as 0.94 +/- 0.02 and 0.58 +/- 0.02 eV, and 27 +/- 2 and 21 +/- 1 (A/cm(2) K-2), respectively, have been calculated from a modified In(I-0/T-2) - q(2)sigma(2)(s)/2k(2)T(2) versus 1/T plot for the two temperature regions. The Richardson constant values are about two times larger than the known value of 14.4 (A/cm(2) K-2) known for n-type InSe. Moreover, in the temperature range 80-320 K, we have also discussed whether or not the current through the junction has been connected with TFE. (c) 2006 Elsevier B.V. All rights reserved.