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

¹ Physics Department, Faculty of Education, Ain Shams University, Roxy, Cairo 11757, Egypt
² Basic Science Department, High Institute of Engineering and Technology, El-Arish, 9004 North Sinai, Egypt

^a e-mail: islamzedan@hotmail.com

Received: 21 April 2012
Accepted: 7 June 2012
Published online: 17 August 2012

Abstract

GaSe₄ films were prepared using thermal evaporation technique onto glass and Si substrates. GaSe₄ 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-GaSe₄/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-GaSe₄/p-Si/Al heterojunction gives the values of effective density of states (N) of 2.4 × 10³⁴ cm⁻³ and the built-in voltage (V_b) of the junction is 0.78 V.