The modeling of p–InxGa1-xN/n–Si hetero junction diodes without using the buffer layer were investigated with the “top-top” electrode. The p–Mg-GaN and p–Mg-In0.05Ga0.95N were deposited directly on the n–Si (100) wafer by the RF reactive sputtering at 400 ◦C with single cermet targets. Al and Pt with the square size of 1 mm2 were used for electrodes of p–InxGa1-xN/n–Si diodes. Both devices had been designed to prove the p-type performance of 10% Mg-doped in GaN and InGaN films. By Hall measurement at the room temperature (RT), the holes concentration and mobility were determined to be Np = 3.45 × 1016 cm-3 and µ = 145 cm2/V·s for p–GaN film, Np = 2.53 × 1017 cm-3, and µ = 45 cm2/V·s for p–InGaN film. By the I–V measurement at RT, the leakage currents at -5 V and turn-on voltages were found to be 9.31 × 10-7 A and 2.4 V for p–GaN/n–Si and 3.38 × 10-6 A and 1.5 V for p–InGaN/n–Si diode. The current densities at the forward bias of 20 V were 0.421 and 0.814 A·cm-2 for p–GaN/n–Si and p–InGaN/n–Si devices. The electrical properties were measured at the temperature range of 25 to 150 ◦C. By calculating based on the TE mode, Cheungs’ and Norde methods, and other parameters of diodes were also determined and compared