Defect recombination induced by density-activated carrier diffusion in nonpolar InGaN quantum wells

Abstract

Abstract:We report on the observation of carrier-diffusion-induced defect emission at high excitation density in a-plane InGaN single quantum wells. When increasing excitation density in a relatively high regime, we observed the emergence of defect-related emission together with a significant reduction in bandedge emission efficiency. The experimental results can be well explained with the density-activated carrier diffusion from localized states to defect states. Such a scenario of density-activated defect recombination, as confirmed by the dependences of photoluminescence on the excitation photon energy and temperature, is a plausible origin of efficiency droop in a-plane InGaN quantum-well light-emitting diodes. a cfzhang@nju.edu.cn b jskwak@sunchon.ac.kr c mxiao@uark.edu

Ultrafast Exciton Dynamics in InGaN/GaN and Rh/Cr2O3 Nanoparticle-Decorated InGaN/GaN Nanowires

“…Likewise, upon the dynamic study of three components TiO 2 -Au-CdS, the Au NPs not only served as an electron relay of charge carriers between CdS and TiO 2 , but also acted as a plasmonic photosensitizer to inject electron into TiO 2 to improve solar-to-chemical energy conversion efficiency 35 The SEM image in Figure 1(a) shows uniform arrays of as-grown p-type InGaN/GaN multiband NWs on Si (111) substrate with an average height of ~600 nm, and diameter of ~40-100 nm. Figure 1 37,38 , which is in good agreement with the defect (or yellow) emission from surface and interface defects along the growth axis of InGaN/GaN NWs reported previously [39][40][41][42] . The PLE spectrum of InGaN/GaN NWs shows strong absorption from 350-450 nm, consistent with previous reports 15,39 .…”

“…Figure 1 37,38 , which is in good agreement with the defect (or yellow) emission from surface and interface defects along the growth axis of InGaN/GaN NWs reported previously [39][40][41][42] . The PLE spectrum of InGaN/GaN NWs shows strong absorption from 350-450 nm, consistent with previous reports 15,39 . The absorption features from 350-375 nm and 375-450 nm can be assigned as the electronic transition from VB to CB of the GaN (~3.4 eV) and the InGaN segments, respectively.…”

Lateral carrier confinement in InGaN quantum-well nanorods

“…5(a), a broadband yellow defect emission together with blue bandedge emission can be detected from the a-plane QW samples under relatively intense pulse excitation [15]. When increasing excitation fluence, the defect emission becomes more important.…”

“…Many factors have been proposed to explain this phenomenon including current leakage, Auger recombination and defect-related mechanisms [14][15][16][17][19][20][21][22][23][24][25][26][27][28][29][30][31]. Vital progresses have been made on suppressing the efficiency droop in the past few years [16,17,20,26,[28][29][30]66].…”

“…Nonetheless, the problem of ''efficiency droop'', i.e., the decrease in quantum efficiency of a LED with increasing carrier density, has persisted since the early demonstration of nitride LEDs in 1990s [14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31]. It becomes even worse with LEDs operating at longer wavelengths (i.e., >500 nm) [19,32], making it challenging to obtain highly efficient white-light emission with nitrides for high power applications.…”