The effect of electron incidence into xenon gas molecules has been investigated by using a nanocrystalline silicon (nc-Si) planar ballistic emitter. Vacuum-ultraviolet light emission is observed without discharging when the nc-Si device is driven in xenon gas. The emission spectrum of xenon at 10 kPa shows peaks at 152 and 172 nm which originate from Xe-2* radiation. These results strongly suggest that energetic electrons directly excite xenon molecules followed by radiative relaxations. The observed effect is potentially applicable to mercury-free, efficient, and stable fiat panel light sources. (C) 2009 American Vacuum Society. [DOI: 10.1116/1.3070655]