Our study examined how native oxide layers, InN and InSb, affected the current-voltage and capacitance-voltage characteristics of the Au/n-InP Schottky diode at a temperature of 300 K with and without interface states, traps, and tunneling current. The simulation was carried out using the Atlas-Silvaco-Tcad device simulator. From our results, we found that the effective barrier heights were measured to be 0.474 eV, 0.544 eV, and 0.561 eV via I-V measurements and 0.675 eV, 0.817 eV, and 0.80 eV via C-V measurements. Additionally, we utilized the high-low frequency method to calculate the average density of interface state density, which was determined to be approximately 6.03 10 11 and 3.33 10 12 сm -2 eV -1 . The results indicate that a thin film of InN and InSb can effectively passivate the InP surface, as evidenced by the good performance of the passivized sample.