Luminescence and lasing in GaN epitaxial layers and InGaN/GaN quantum wellheterostructures under optical and electron-beam excitation

Interrelation between stimulated and excitonic emission intensity of GaN ep itaxial layers and yellow luminescence intensity as well as correlation bet ween photoluminescence and laser properties of InGaN based multiple quantum well heterostructures was investigated. It was found among all studied und oped GaN epitaxial layers that the higher intensity of the yellow luminesce nce and so the higher concentration of the yellow luminescence related cent res the higher is tile excitonic, electron-hole plasma and stimulated emiss ion intensity, It was shown that a small Stokes shift and a high ratio of t he luminescence intensity from InGaN quantum well layers to the photolumine scence intensity from GaN barrier layers indicate high laser quality of the multiple quantum well heterostructures. The lowest full width at half maxi mum of the laser line was 0.04 nm. the highest operating temperature was 58 5 K, the lowest threshold was 100 kW cm(-2). the highest characteristic tem perature was 164 K and the highest wavelength was 442.5 nm. The far-field p atterns of the laser emission from the MQW lasers consist of two approximat ely symmetrical high brightness spots localized at angles alpha = +/- 30-35 degrees. (C) 2001 Elsevier Science B.V. All rights reserved.