MBE grown InGaN quantum dots and quantum wells: effects of in-plane localization

InGaN/GaN heterostructure samples were grown by molecular beam epitaxy usin g ammonia as a nitrogen precursor. The growth of InGaN/GaN self-assembled q uantum dots was monitored in situ by reflection high energy electron diffra ction intensity oscillations. Atomic force microscopy scans showed a very h igh density of InGaN islands, similar to 1x10(11) cm(-2), well above the di slocation density. This could explain the increased radiative efficiency of these samples compared to homogeneous quantum wells. Light emitting diodes (LEDs) with InGaN active layers buried in GaN were realized. Electrolumine scence and photocurrent spectra of these LEDs evidence a strong Stokes shif t that can be attributed to high localization of carriers in InGaN layers. (C) 2000 Elsevier Science B.V. All rights reserved.