Preparation and characterization of Au/n-GaSe4/p-Si/Al Schottky-type thin film heterojunctions

Abstract

GaSe 4 films were prepared using thermal evaporation technique onto glass and Si substrates. GaSe 4 in both ingot and thin films was studied by hot probe procedure indicated n -type semiconductor. The conductivity activation energy ( ΔE ) decreased from 0.414 to 0.365 eV with the increase in film thickness from 90 to 500 nm. Investigation of the heterojunction n -GaSe 4 / p -Si by using characteristics indicated good rectification with rectification ratio of 48 at room temperature and at V = ±1.6 V. The ideality factor decreased from 2.2 to 2.13 while the reverse saturation current decreased from 8.3 × 10 −7 A to 3.27 × 10 −7 A by the temperature rise from 310 to 363 K. For lower and higher values of applied voltage, Pool-Frenkel and Schottky coefficients were 2.2 × 10 −5 and 0.7 × 10 −5 eV m −1/2 , beside that, Schottky barrier height was found to be 0.4 eV. The thermionic emission mechanism occurs in the low forward voltage range but in the high forward region, the space-charge-limited current (SCLC) controlled by a single trap level is the dominant mechanism. In the reverse direction the Poole-Frenkel mechanism is the operating mechanism. Analysis of C-V characteristics of Au/ n -GaSe 4 / p -Si/Al heterojunction gives the values of effective density of states ( N ) of 2.4 × 10 34 cm −3 and the built-in voltage ( V b ) of the junction is 0.78 V.