PHOTOVOLTAIC EFFECTS FROM POROUS SI

The photovoltaic (PV) effects from sandwiched porous silicon (PS), fab ricated using electrochemical etching processes, have been investigate d. Contacts were made by bonding to semi-transparent coatings of Au vi a a secondary supportive Al contact. The contribution of the PV effect s from the junctions of the metal (Au)/n-type and p-type PS, and partl y from the PS/bulk Si heterojunction, was observed for the visible wav elength range of light, and under white light of different powers. Som e optical and electrical characteristics of various PV devices have be en measured under a range of optical powers. Photovoltages of some of the PV devices with different preparation conditions were measured as a function of UV/VIS excitation energies. The polarities of photovolta ge for both types (n- and p-PS) of device were found to be the same. T he external quantum efficiencies of the PV devices are also presented.