LIGHT-EMISSION FROM SI-METAL-OXIDE-SEMICONDUCTOR TUNNEL-JUNCTIONS

We have observed visible light emission from Si-Metal-Oxide-Semiconductor (MOS) tunnel junctions with a thin oxide barrier (6.6 nm). The junction consists of a phosphorous diffused n-type layer in a p-type Si wafer, a SiO2 layer as the tunnel barrier, and an evaporated metal film (Au or Al) as the counter electrode. The current-voltage characteristics of these junctions are well described by the Fowler-Nordheim tunneling theory. The emission spectra are independent of the bias voltage polarity, but depend on the counter electrode material. After examining different possible emission mechanisms, we conclude that the surface plasmon mechanism that is operative in metal-oxide-metal (MOM) light emitting tunnel junctions is the most important process of light emission in the MOS junctions also.