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Investigation of V-Defects and embedded inclusions in InGaN/GaN multiple quantum wells grown by metalorganic chemical vapor deposition on (0001) sapphire

2003; American Institute of Physics; Volume: 83; Issue: 1 Linguagem: Inglês

10.1063/1.1588370

1520-8842

D. I. Florescu, S. M. Ting, J. Ramer, D. S. Lee, V. Merai, A. Parkeh, Dongzhu Lu, E. Armour, Leonid Chernyak,

Ga2O3 and related materials

We have examined the nature of V-defects and inclusions embedded within these defects by atomic force microscopy (AFM) and high-resolution scanning electron microscopy (SEM)/cathodoluminescence (CL) in InGaN/GaN multiple quantum wells (MQWs). To date, indium distribution nonuniformity in the well or GaN barrier growth temperature have been identified as the main factors responsible for the V-defect occurrence and propagation. Further complicating the matter, inclusions embedded within V-defects originating at the first InGaN-to-GaN interface have been observed under certain growth conditions. Our AFM and high-resolution SEM/CL findings provide evidence that some V-defects occur merely as direct results of barrier temperature growth, and that there are additional V-defects associated with In-rich regions, which act as sinks for further indium segregation during the MQW growth. Both types of V-defects have a tendency of promoting inclusions at low-temperature (800 °C) GaN barrier growth in an H2-free environment. Localized strain-energy variations associated with the apex of V-defects may be responsible for the inclusion occurrence. Adding H2 during the GaN barrier growth reduces V-defect formation and suppresses inclusion propagation entirely, rendering a uniform nanoscale CL signal.