Porous silicon light-emitting diodes – mechanisms in the operation

Abstract Although electroluminescence (EL) in porous silicon (PS) had been demonstrated by a number of groups, there is lack of a generally accepted, consistent explanation of the conditions for light emission. In this work the mechanisms involved are discussed by studying the temperature-dependent behaviour of PS light-emitting diode (LED) devices fabricated in anodised p-type and n-type Si substrates. The indium tin oxide (ITO)–porous Si–crystalline Si structure was characterised in vacuum by recording the I – V characteristics and the simultaneous light emission at different temperatures. The temperature dependence originates from the porous–single crystal heterojunction and the conduction in the structure, while occurrence of EL requires the dominance of Fowler–Nordheim (FN) tunneling in PS. By identifying the different temperature-dependent I – V regions, an equivalent circuit for the PS LEDs will be proposed.