Factors Affecting Light Emission from Solid State Incandescent Light Emitting Devices with Sputter Deposited Zr-Doped HfO2 Thin Films

Abstract

The light emission characteristics of a new type of solid state light emitting device, which is based on the thermal excitation of conductive paths formed in the Zr-doped HfO2 high-k dielectric stack, have been investigated with respect to the fabrication process, film properties, the device driving method, and the lifetime. The emission spectrum covers the visible to the near IR wavelength range with a high color rendering index of 98.1. The light intensity increases with the increase of the post deposition annealing temperature due to changes of the film thickness and defect density. It also increases with the increase of the magnitude of the driving voltage because of the enhancement of the thermal excitation of the conductive path. The light emission intensity decreases with the reduction of the duty cycle in the pulsed driving condition but the emission spectrum remains in the same wavelength range. This device has a very long lifetime of >2,800 hours in the atmosphere. This new device is made of the IC compatible material and fabrication process, which favors the application in a wide range of products.