Ultraviolet Light Emission from Si in a Scanning Tunneling Microscope

Abstract

Ultraviolet and visible radiation is observed from the contacts of a scanning tunneling microscope with Si(100) and (111) wafers. This luminescence relies on the presence of hot electrons in silicon, which are supplied, at positive bias on n- and p-type samples, through the injection from the tip, or, at negative bias on p samples, by Zener tunneling. Measured spectra reveal a contribution of direct optical transitions in Si bulk. The necessary holes well below the valence band edge are injected from the tip or generated by Auger processes.

Luminescence experiments on supported molecules with the scanning tunneling microscope

“…Concerning semiconductor surfaces, carriers are elastically injected from the tip into the sample. The recombination process can give rise to emission of light [129,130,101,131]. It is interesting to note that the linear polarization of light emission from a tunneling gap formed by a W tip and a Si(001)-(2 × 1) surface strongly depends on the bias voltage.…”

Silicon coupled with plasmon nanocavities generates bright visible hot luminescence

“…In bulk silicon, emission from hot-carriers (non-thermalized carrier recombination) has been observed by injecting carriers at large applied bias 10 ; however, the measured quantum efficiency is extremely low because hot-carrier relaxation time (intra-band; 0.1–1 ps) is much faster than radiative lifetime (∼10 ns) 11–14 , leading to very poor efficiency (<10 −4 ) for hot-luminescence across the direct band at the Γ point. However, visible light emission from hot-carriers in “bulk” silicon can be efficient if the radiative lifetime becomes comparable with the hot-carrier relaxation time.…”

Giant photoluminescence emission in crystalline faceted Si grains

“…Previous observations of ultraviolet and visible radiation emission from Si were reported from the contacts of a scanning tunneling microscope. This luminescence relies on the presence of hot electrons in silicon on phononless emission from bulk in the range 2–5 eV15. In nanostructured Si, photoluminescence spectrum of silicon nanocrystals were reported with increasing intensity and shift to longer wavelengths with smaller nanocrystal sizes.…”