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

摘要

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) under zero electrical field, and 1.31 ± 0.01 eV (at 10 K) and 1.26 ± 0.01 eV (at 300 K) under 6000 Vcm~(-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) Φ_(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 Φ_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, Φ_(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 ln(I_0/T~2) - q~2σ~2/2k~2T~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.