Exciton localization in semipolar (112¯2) InGaN multiple quantum wells

Abstract

The exciton localization in semipolar (112⎯⎯2112¯2) InxGa1−xN (0.13 ≤ x ≤ 0.35) multiple-quantum-well (MQW) structures has been studied by excitation power density and temperature dependent photoluminescence. A strong exciton localization was found in the samples with a linear dependence with In-content and emission energy, consistent with the Stokes-shift values. This strong localization was found to cause a blue-shift of the MQW exciton emission energy at temperature above 100 K, which was found to linearly increase with increasing In-content

Role of substrate quality on the performance of semipolar (112¯2) InGaN light-emitting diodes

“…The blue-shift of 1.8 nm with increasing I inject can be explained by the QCSE and band-filling effect. [1][2][3][23][24][25][26][27][28] For $430 nm polar and $425 nm (10 11) InGaN LEDs, 29 blue-shifts of 3.5 nm and 1.5 nm have been reported, respectively. This smaller blue-shift value of the (10 11) InGaN LED was attributed mainly to a weaker QCSE than the polar LED.…”

“…A similar finding has been previously reported for (11 22) In x Ga x N QWs (0.13 x 0.35). 27,28 To estimate the ELOC degree of both samples, a modified Varshni empirical expression 24,[26][27][28] was used to fit the E PL values within the temperature range of 160-400 K. The estimated ELOC degree of both samples was about 40 meV. This ELOC degree is higher than the values of $12-24 meV previously reported for $460 nm polar MQW.…”

“…The higher In-incorporation InGaN regions, e.g., the red-shifted areas should act as ELOC areas in which diffusing carriers can be trapped. [23][24][25][26][27][28] The ELOC areas in the PSS-LED are darker, which can explain its lower IQE in comparison with the Bulk-LED where ELOC areas are brighter.…”