Synchrotron-radiation-induced surface photovoltage on GaAs studied by contact-potential-difference measurements

We used the Kelvin method to study the synchrotron-radiation-induced surface photovoltage (SPV) on GaAs(110) and its impact on the photoemission study of metal-semiconductor interfaces formed at low temperature. We find that varying the temperature alone does not induce significant change in band bending in the semiconductor, but that the combination of low temperature and synchrotron-light illumination on lightly doped n-type GaAs induces a large and quasipermanent SPV. It is also found that low-intensity stray light can induce measurable SPV on these samples. Highly doped low-temperature p-type GaAs does not exhibit significant SPV under synchrotron-radiation illumination.