ELECTRICAL QUENCHING OF PHOTOLUMINESCENCE FROM POROUS SILICON

We have studied the visible photoluminescence (PL) of porous silicon ( PS) under the condition that a bias voltage is applied in the directio n of the PS layer thickness. It is shown, for the first time, that the PL intensity is sharply decreased when increasing the voltage. This e lectrical PL quenching was completely reversible. This phenomenon is i nterpreted as to arise from field-enhanced tunneling of carriers betwe en silicon crystallites. The result presented here strongly suggests t hat the visible luminescence of PS is not based on electronic transiti ons in some molecular substance, but on the radiative recombination in Si nanocrystallites.