Stable and efficient electroluminescence from a porous silicon-based bipolar device

A complete process compatible with conventional Si technology has been developed in order to produce a bipolar light-emitting device. This device consists of a layer of light-emitting porous silicon annealed at high temperature (800-900°C) sandwiched between a p-type Si wafer and a highly doped (n+) polycrystalline Si film. The properties of the electroluminescence (EL) strongly depend on the annealing conditions. Under direct bias, EL is detected at voltages of ∼2 V and current densities J∼1 mA/cm2. The maximum EL intensity is 1 mW/cm2 and the EL can be modulated by a square wave current pulse with frequencies ν≥1 MHz. No degradation has been observed during 1 month of pulsed operation.