High brightness blue and green light emitting quantum wells with graded‐In‐content profile grown by MOCVD

Abstract

Graded-In-content InGaN/GaN quantum wells (QWs) with high brightness blue and green emission were grown on sapphire by metalorganic chemical vapor deposition. The optical properties were studied by temperature-dependent photoluminescence (PL), PL excitation (PLE), and time-resolved PL. Phase separations are revealed by PL measurement and verified by PLE with different absorption edges. From temperature-dependent PL, the integrated intensity of the main InGaN blue and green emission (∼462 nm for blue and ∼509 nm for green) decreased by about a factor of 13.2 and 7.4, only about one order of magnitude, with increasing temperature from 10 to 300 K, indicating strong carrier localization and high quantum efficiency in graded-In-content multiple QWs. Time-resolved PL shows a clear increase of decay time with temperature from 14 to 90 K for blue emission samples and to 50 K for green emission samples, then decrease with more higher temperature. From the time-resolved PL results, a clear carrier transfer is observed from weakly to strongly localized states, which plays an important role to enhance brightness and quantum efficiency in graded-In-content InGaN QWs. (© 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)