We have fabricated the Al/SnO2/p-Si (111) Schottky diodes having the SnO2/P-Si heterojunction prepared using the spray deposition process at various Si substrate temperatures and report the first investigation of the energy distribution of the interface state density of these diodes. The barrier height OB estimated from the I-Vand C-V measurements agrees with each other and increased with increasing substrate temperature. The energy distribution of interface state density N-ss was determined from the forward bias I-V characteristics by taking into account the bias dependence of the effective barrier height. The interface state density N-ss of the diodes has an exponential growth with bias from the midgap towards the top of the valance band for each diode; for example, from 1.46 x 1012 eV(-1) cm(-2) in (0.46 - E-v) eV to 1.29 x 1012 eV(-1) cm(-2) in (0.53 - E-v) eV for SD3 sample. (c) 2004 Elsevier B.V. All rights reserved.