Carrier transport in porous silicon light-emitting devices

This work presents a comprehensive investigation of carrier transport properties in light-emitting porous silicon (LEPSi) devices. Models that explain the electrical characteristics and the electroluminescence properties of the LEPSi devices are developed. In metal/LEPSi devices, the forward current density-voltage (J-V) behavior follows a power law relationship (J similar to V-m), which indicates a space charge current attributed to the carriers drifting through the high resistivity LEPSi layer. In LEPSi pn junction devices, the forward J-V behavior follows an exponential relationship (J similar to e(eV/nkT)), which indicates that the diffusion of carriers makes a major contribution to the total current, The temperature dependence of the J-V characteristics, the frequency dependence of the capacitance-voltage characteristics, and the frequency dependence of the electroluminescence intensity support the models. Analysis of devices fabricated with a LEPSi layer of 80% porosity results in a relative permittivity of similar to 3.3, a carrier mobility of similar to 10(-4) cm(2)/V s, and a free carrier concentration of similar to 10(13) cm(-3). (C) 1996 American Institute of Physics.