Chan Lesley, Karmstrand Therese, Chan Aaron, Shapturenka Pavel, Hwang David, Margalith Tal, DenBaars Steven P, Gordon Michael J
Opt Express. 2020 Nov 9;28(23):35038-35046. doi: 10.1364/OE.403299.
Nanoscale light emitting diodes (nanoLEDs, diameter < 1 µm), with active and sacrificial multi-quantum well (MQW) layers epitaxially grown via metal organic chemical vapor deposition, were fabricated and released into solution using a combination of colloidal lithography and photoelectrochemical (PEC) etching of the sacrificial MQW layer. PEC etch conditions were optimized to minimize undercut roughness, and thus limit damage to the active MQW layer. NanoLED emission was blue-shifted ∼10 nm from as-grown (unpatterned) LED material, hinting at strain relaxation in the active InGaN MQW layer. X-ray diffraction also suggests that strain relaxation occurs upon nanopatterning, which likely results in less quantum confined Stark effect. Internal quantum efficiency of the lifted nanoLEDs was estimated at 29% by comparing photoluminescence at 292K and 14K. This work suggests that colloidal lithography, combined with chemical release, could be a viable route to produce solution-processable, high efficiency nanoscale light emitters.
通过金属有机化学气相沉积外延生长有源和牺牲多量子阱（MQW）层的纳米级发光二极管（nanoLED，直径<1μm），采用胶体光刻和牺牲MQW层的光电化学（PEC）蚀刻相结合的方法制造并释放到溶液中。优化PEC蚀刻条件以最小化底切粗糙度，从而限制对有源MQW层的损伤。与生长时（未图案化）的LED材料相比，纳米LED发射的光蓝移了约10nm，这表明有源InGaN MQW层中的应变弛豫。X射线衍射还表明，纳米图案化时会发生应变弛豫，这可能导致量子限制斯塔克效应减小。通过比较292K和14K下的光致发光，估计提升后的纳米LED的内量子效率为29%。这项工作表明，胶体光刻与化学释放相结合，可能是生产可溶液处理的高效纳米级发光体的可行途径。
