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.