Abstract
CaSe4 films were prepared using thermal evaporation technique onto glass and Si substrates. CaSe4 in both ingot and thin films was studied by hot probe procedure indicated n-type semiconductor. The conductivity activation energy (Delta E) 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 x 10(-7) A to 3.27 x 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 x 10(-5) and 0.7 x 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-CaSe4/p-Si/AI heterojunction gives the values of effective density of states (N) of 2.4 x 10(34) cm(-3) and the built-in voltage (V-b) of the junction is 0.78 V.