a1 Physics Department, Faculty of Education, Ain Shams University, Roxy, Cairo 11757, Egypt
a2 Basic Science Department, High Institute of Engineering and Technology, El-Arish, 9004 North Sinai, Egypt
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 (Vb) of the junction is 0.78 V.
(Received April 21 2012)
(Accepted June 07 2012)
(Online publication August 17 2012)