Femtosecond Carrier Dynamics at InP/Liquid Interfaces in the Presence of Electric Fields

Recently there has been considerable interest in studying photogenerated carrier dynamics in semiconductors under the influence of electric fields1. This is a process of critical importance in recombination kinetics and electron transfer processes at semiconductor interfaces. At semiconductor-liquid interfaces, very large electric fields (typically 105 to 106 volts/cm) exist in the semiconductor close to its surface because of the formation of a space charge layer (SCL)2. Externally-applied potentials will drop across the SCL to increase or decrease the space charge fields (SCFs) and the surface band bending-VB. Under bandgap illumination the SCFs are reduced because of screening by the photogenerated majority carriers, but strong residual SCFs are ubiquitous across any semiconductor liquid interface. It is expected that these SCFs may have a crucial role in electron transfer (ET) processes at semiconductor electrodes.