Characterization of the M.S structure by the surface photoelectrical voltage method

Photovoltages (surface photovoltage plus Dember voltage) were calculated, taking into consideration the influence of charge exchange between a continuum of surface states and the semiconductor, the barrier lowering as a result of the Schottky effect, the applied voltage drop and transmission coefficient across the interfacial layer. For moderate band bending, the photovoltage depends on several parameters which renders their reliable determination very difficult. For extreme band bending, however, only doping factor, mobility ratio and relative excess concentration enter into given formulas. The obtained analytical expression includes saturation effects at the surface, so that the photovoltage (SPV) does not exceed the thermodynamic band bending. The bulk effect of the Dember voltage is then added to obtain the relationship between the light generated current and open circuit voltage at the terminals. Results were applied to Schottky barrier diodes Au/InP(n). The InP substrate is restructured by some monolayers of InSb thin film [L. Bideux, B. Gruzza, A. Porte, H. Robert, Surface and Interface Analysis 20 (1993) 803]. Good agreement between parameters determined in this way and otherwise indicates the validity of the model and the approximations used in this work.