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In this paper, we report on the results of experimental and theoretical study of a promising way for suppression of the efficiency droop with current in InGaN-based light emitting diodes. Simulations carried out using a drift-diffusion approach with quantum-mechanical corrections clearly show that nonradiative Auger recombination is the principal mechanism limiting the device performance at high-injection level. New design of LED heterostructure with short-period superlattice in the active region is proposed and assessed theoretically. Experimentally, the implementation of the structure design in high-power devices has resulted in substantial suppression of the efficiency droop compared to conventional multiquantumwell InGaN LEDs.

AbstractOver the last five years, inorganic lead halide perovskite nanowires have emerged as prospective candidates to supersede standard semiconductor analogs in advanced photonic designs and optoelectronic devices. In particular, CsPbX3 (X = Cl, Br, I) perovskite materials have great advantages over conventional semiconductors such as defect tolerance, highly efficient luminescence, and the ability to form regularly shaped nano- and microcavities from solution via fast crystallization. However, on the way of electrically pumped lasing, the perovskite nanowires grown on transparent conductive substrates usually suffer from strong undesirable light leakage increasing their threshold of lasing. Here, we report on the integration of CsPbBr3 nanowires with nanostructured indium tin oxide substrates possessing near-unity effective refractive index and high conductivity by using a simple wet chemical approach. Surface passivation of the substrates is found out to govern the regularity of the perovskite resonators’ shape. The nanowires show room-temperature lasing with ultrahigh quality factors (up to 7860) which are up to four times higher than that of similar structures on a flat indium tin oxide layer, resulting in more than twofold reduction of the lasing threshold for the nanostructured substrate. Numerical modeling of eigenmodes of the nanowires confirms the key role of low-refractive-index substrate for improved light confinement in the Fabry–Pérot cavity which results in superior laser performance.

In this paper we report on fabrication of high power InGaN based blue light emitting diodes (LEDs) with substantially suppressed efficiency droop. The key feature of proposed device is the utilization of short‐period superlattice in the active region of LED heterostructure. In this superlattice the GaN barriers between quantum wells (QWs) are transparent for tunnelling, thus enabling carrier delocalization in growth direction. This, in turn, leads to the reduction of carrier concentration at given pumping comparing to the standard LED heterostructure, where, usually, only one QW contributes to light emission. The reduction of carrier concentration results in substantial suppression of third order non‐radiative processes, such as Auger recombination, responsible for the efficiency droop at high pumping. As a result, the LED external efficiency at operating current 350 mA differs from its maximum value only by 7%. Also, fabricated LEDs demonstrate very good stability of spectral position of the emission line, the observed blue shift of electroluminescence being less than 1 nm at pumping up to 1000 mA. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)