ELECTROCHEMICAL INVESTIGATIONS OF SILICON BORON PHOSPHIDE HETEROJUNCTION PHOTOELECTRODES/

An electrochemical study of Si/BP heterojunction photoelectrodes was u ndertaken in order to explore the feasibility of utilizing such electr odes in liquid junction solar cells. It appears that in the case of n- type Si/n-type BP heterostructures, only low photocurrent densities ar e produced by the electron-hole pairs generated in the wide-bandgap BP window. In contrast, p-type Si/n-type BP heterojunctions show large c athodic photocurrents upon irradiation with visible light. Detailed im pedance analysis was carried out to derive the band diagrams of the tw o studied configurations. It appears that an excellent match between t he conduction bands of Si and BP is present, which explains the observ ed effects. In addition, surface trapping and recombination phenomena at the BP/electrolyte interface were explored with impedance technique s.