Spatially resolved photoluminescence in InGaN/GaN quantum wells by near-field scanning optical microscopy

Spatially and spectrally resolved photoluminescence (PL) from InGaN/GaN qua ntum wells is obtained using near-field scanning optical microscopy (NSOM). Samples displaying high macroscopic PL intensity revealed nonuniform inten sity and linewidth but nearly uniform peak position. It suggests that the c ontrast in the NSOM image reflects nonuniform distribution of dislocations or defects which act as nonradiative recombination centers. The formation o f quantum dots with size of 30 +/- 25 nm and their size-dependent interacti on with dislocations were observed in plan-view transmission electron micro scopy. It is likely that the high luminescence efficiency is due to the eff icient localization of excitons in high-density quantum dots located in reg ions with fewer dislocations. (C) 2001 American Institute of Physics.