Efficient injection mechanism for electroluminescence in GaN

GaN electroluminescent devices have been realized with external quantum efficiency close to 1% in the yellow and 0.3% in the green. The active region is composed of two zinc‐doped layers, n type and semi‐insulating (1000 A), and a metal contact. Electroluminescence is obtained with voltages of 5–10 V typically and values as low as 2.5 to 4 V have been obtained (+ on the metal). A model is proposed to explain the injection in this structure; it involves impurity band conduction and electron injection from the (n) to (i) side. The I (V) characteristic is found to follow the Frenkel‐Poole law.