In this article, a 2-D TCAD simulation study on the forward and reverse characteristics of oxygen-terminated diamond (D:O) m-i-p+ Schottky barrier diode (SBD) is carried out considering the effects of Fermi level pinning due to surface states (SSs) and metal-induced gap states (MIGS). The device simulation considers drift-diffusion transport, SS charge neutrality level (CNL), MIGS through Fermi level pinning parameter (S), doping and temperature-dependent mobility model, incomplete ionization of dopants, and impact ionization models. The simulation validation is carried out for Al/Au Schottky metals at room temperature and at higher temperatures. A good comparison between the simulation and experiment is obtained around turn-on voltage (V T0∼ 1.0 V for Al and 2.0 V for Au Schottky contacts) and for anode voltage (VA) > VT 0. Through simulations, we estimated the type of SSs and their quantity, and the position of CNL (ECNL) within the diamond bandgap. The effect of ECNL position and pinning parameter on the forward and reverse characteristics is also simulated. The impact of ECNL and SS on reverse leakage current is also analyzed using a nonlocal barrier tunneling model. At higher temperatures, a good match between simulation and experiment of forward characteristics is achieved. © 1963-2012 IEEE.