V-defects formation and optical properties of InGaN/GaN multiple quantum well LED grown on patterned sapphire substrate

摘要

To enhance light extraction efficiency, high quality InGaN/GaN multiple quantum well (MQW) LED was grown on cone shaped patterned sapphire substrate (CPSS) by using metal organic chemical vapor deposition (MOCVD). In the growth of InGaN multiple quantum well structure, all V-defects are not always connected with threading dislocations (TDs) at their bottom, also many V-defects are generated from the stacking mismatch boundaries induced by stacking faults which are formed within the MQW due to the strain relaxation. The formation of the V-defect is kinetically controlled by reduced Ga incorporation on the pyramid walls ({10 (1) over bar1} planes). The improvement of luminous intensity and reverse I-V characteristic (the leakage currents of the LEDs grown on CPSS and USS were -0.23 mu A and -0.76 mu A, respectively, at the reverse voltage of -10 V) was explained by considering not only an increase of the extraction efficiency via the suppressed total internal reflection a the CPSS interface but also a decrease of V-defect density. (C) 2013 Elsevier Ltd. All rights reserved.