PHOTOVOLTAIC RESPONSE IN ELECTROCHEMICALLY PREPARED PHOTOLUMINESCENT POROUS SILICON

Using the electrochemical procedure for the production of porous Si, material is produced which shows a solid state photovoltaic response. Under simulated sunlight, the open circuit voltage is near 0.36 V and the photocurrent is near 2-mu-A. The current-voltage characteristics exhibit a high series resistance which is on the order of 1 M-OMEGA. The spectral response is characteristic of the silicon itself, and suggests that a heterojunction is formed between the high effective bandgap porous silicon and the bulk p-silicon wafer. Time resolved photoconductivity measurements indicate that the porous Si material is characterized by a high recombination rate. At low excess carrier density there is a barrier to this recombination which is tentatively ascribed to band bending and carrier injection at the porous Si/crystalline Si interface.