Ds. Joag et al., FIELD ELECTRON-EMISSION FROM HYDROGENATED AMORPHOUS-SILICON FILMS ON TUNGSTEN - LIGHT-INDUCED EFFECTS, Applied physics letters, 64(25), 1994, pp. 3437-3439
Field electron emission from a hydrogenated amorphous silicon deposite
d tungsten tip has been studied. The effect of prolonged (hourly) expo
sure to light on the field electron emission current has been investig
ated. The current-voltage characteristics of the as-deposited, light e
xposed, and annealed states of the emitter showed semiconducting behav
ior in accordance with the Fowler-Nordheim law. In case of an initiall
y annealed emitter tip, the field emission current was found to increa
se monotonically with the light exposure, reversibly for shorter durat
ions of a few minutes. The effect of long term (hourly) exposure of li
ght resulted in the increase in the field emission current level nonli
nearly with the exposure time. The current level did not come down to
the original level even after switching off the light in contrast to t
he effect of short duration light exposure. The enhancement in the fie
ld emission current has been attributed to tunneling though the dangli
ng bond states created by light exposure. The results have been discus
sed in light of the Staebler-Wronski effect.