GaN electroluminescent diodes

Luminescence in GaN has been reported thus far only when the material was excited with an electron beam or ultraviolet radiation. The present work is an extension of our recent discovery of electroluminescence under point contacts. GaN diodes of the i-n (insulating-to-n-type) variety have been made by Zn-doping. These exhibit green dc electroluminescence at room temperature. The light emitted is due to a transition to a deep level in this direct wide gap semiconductor. The radiated output is proportional to the input power; the external power efficiency is 10^-4; an external quantum efficiency of one per cent has been obtained. The response time of several microseconds is limited mostly by the RC time constant of the structure. Photovoltaic measurements indicate a barrier height of about 1.6 eV at the i-n structure.