Ultraviolet emission of silicon quantum tips

Silicon tips used as field emitters have dimensions that are within the quantum confinement regime. Therefore they can be considered as freestanding silicon tips. In this letter, a photoluminescence spectrum of a 100× 1000 array of silicon tips was taken at 10 K. Narrow ultraviolet luminescence peaks were observed. Using the empirical pseudopotential homojunction model, it is demonstrated that these luminescence peaks come from energy levels arising from quantum confinement. By fitting the theoretical result to the experimental result, we conclude that the luminescence peaks come from Si quantum tips of about 20 Å in width and that they are covered by silicon dioxide.