Comparison of Light-Emission Efficiencies from Si–Metal-Oxide-Semiconductor Junctions and from Si in Scanning Tunneling Microscopy

Abstract

We have investigated the mechanism of scanning tunneling microscope (STM) visible light emission from n-type Si(100). The current fluctuation theory that explained the light emission characteristics of the Si–metal-oxide-semiconductor (Si–MOS) tunnel junction is applied to the STM light emission from n-type Si(100). This theory reproduces the observed STM light emission spectra, and predicts that the light emission efficiency from the STM geometry is ∼1.5×104 times greater than that from the Si–MOS junctions. This prediction is consistent with our experimental result. Experimentally, the light emission intensity from the Si surface under the STM is comparable to that from the Si–MOS junction, although the tunneling current in the STM is 10-3 of the current in the Si–MOS junction. That is, the light emission efficiency from the STM is at least 103 times greater than that from the Si–MOS.