Electrical, photoelectrical and electroluminescent properties of porous Si-c-Si heterojunctions

Porous silicon-c-Si heterojunctions have been formed by the method of stain etching. A ZnO highly conductive thin film was used as a front transparent contact. The transport mechanism, photovoltaic and electroluminescent properties have been studied. The heterojunctions show a wide spectral response, from 400 to 1000 nm. The spectral dependence of the photocurrent in the region 400-600 nm depends on the reverse bias. Electroluminescence from the device structure in the visible region has been observed under forward bias. A model based on tunneling of minority carriers through a narrow energy barrier between ZnO and porous Si and the presence of a spike barrier and a conduction band discontinuity at the interface porous Si/c-Si is suggested for describing the properties of the heterojunctions. (C) 1997 Elsevier Science S.A.