White light emission from ultrathin tungsten metal oxide film

White light emission from a metal–oxide–semiconductor capacitor with the sub-5 nm thick tungsten oxide dielectric film deposited on a p-type silicon wafer has been observed and studied. Light covering the whole visible wavelength range was emitted when the device was stressed with a negative gate voltage after the breakdown of the dielectric stack. The principle of light emission is similar to that of the incandescent lamp, i.e., thermal excitation of the conductive path. The light intensity increased with the increase of the magnitude of the stress voltage in the DC stressing condition or the duty cycle in the pulsed driving scheme. The emitted light had a high color rendering index of 95 and stable International Commission on Illumination coordinates over a large range of stress voltages. The light emission process had lasted for more than 1300 h continuously in air without failure except the minor decrease of the intensity. This kind of device can be used in many areas such as commercial, industrial, medical, etc.