We have investigated the electroreflectance (ER) and photoreflectance (PR) spectra from the space-charge region (SCR) of the model Schottky- barrier system (In2O3)0.91(SnO2)0.09 on p-type InP [(In-Sn-O)/InP]. Both ER and PR were studied as a function of reverse dc bias, Vbias. The observed Franz-Keldysh oscillations provide a direct measure of the surface dc electric field, scrEdcs. The ac modulating voltage (for small modulation) affects only the envelope of the FKO but not the period. A generalized Franz-Keldysh theory, taking into consideration the presence of dc fields, accounts for the above experimental results. From a plot of (scrEdcs)2 as a function of Vbias we have obtained the built-in potential and net carrier concentration of the structure. Our work demonstrates that electromodulation in Schottky barriers can be used as an optical Mott-Schottky method.
ASJC Scopus subject areas
- Condensed Matter Physics