Emission and recombination characteristics ofGa1−xInxN∕GaNquantum w

Abstract

We demonstrate quantitatively that the realization of high internal quantum efficiency of more than 70% at room temperature in GaInN / GaN quantum well structures is possible with potential barriers, which are caused by V-shaped pit formation around threading dislocations. Localization of charge carriers is present in the samples, but its contribution to room temperature quantum efficiency is negligible. The emission and recombination characteristics of GaInN / GaN quantum well structures with deep V-shaped pits are studied in detail. Due to narrower wells and smaller piezoelectric fields, the GaInN quantum wells on the facets of extended V-shaped pits emit several hundred meV higher in energy than the c-plane quantum wells. Because of the simultaneous growth, the emission energies of the c-plane and the V-shaped pit quantum wells are correlated. The relative intensity of both emissions depends on the ratio between the c-plane and the V-shaped pit surface area during GaInN quantum well growth. GaInN / GaN LED structures from different commercial sources feature V-shaped pits and their effects on the emission characteristics, too. Hence, a universal relevance of V-shaped pit potential barriers around dislocations in GaInN / GaN heterostructures for high internal quantum efficiency is suggested.

Internal quantum efficiency of III-nitride quantum dot superlattices grown by plasma-assisted molecular-beam epitaxy

“…), have led to strong controversy about the light emission mechanisms and their correlation with structural properties. [1][2][3][4][5] To assess the optical quality of these structures, the internal quantum efficiency (IQE) is often used as a reference parameter. IQE is defined as IQE ¼ R R /(R R þ R NR ), with R R and R NR being the radiative and nonradiative recombination rates, respectively.…”

“…This S-shaped variation is associated with potential fluctuations in the QWs: the blueshift at intermediate temperatures is explained by the filling of potential valleys with different depths upon excitation. 2,5,[34][35][36] In the case of GaN/AlN QWs, the potential fluctuations responsible for this behavior can be related to variations in the QW thickness or/and to the presence of structural defects. The remarkable enhancement of the S-shape in InGaN QWs points to alloy inhomogeneities.…”

Comparison of electrostatic and localized plasmon induced light enhancement in hybrid InGaN/GaN quantum wells

“…The narrower quantum wells result in an increase in the bandgap within the pits and results in the formation of a potential barrier that effectively shields carriers from the non-radiative recombination center at the center of the IHP. 2,15 The IHPs were filled with Au or Ag nanoparticles as shown in Figure 1. The IHPs provide a means by which to place the NPs deep within the MQW without damaging the structure of the quantum wells.…”

“…15 The PL spectrum for a reference sample without any metal nanoparticles is shown in Figure 3(a). The narrowing of the QWs results in a distinct emission at a higher energy, which may be extracted via a Gaussian fit of the spectra.…”

Reduction of Current Crowding in InGaN-based Blue Light-Emitting Diodes by Modifying Metal Contact Geometry

“…The InGaN-based blue LEDs show the significant reduction of internal quantum efficiency called 'efficiency droop' when the current level increases. Over the past years, there have been many researches to analyze and improve the efficiency droop of the LEDs [1][2][3][4][5][6][7][8]. It is known that current crowding is one of the major obstacles to solving the droop problem and increasing internal quantum efficiency [9,10].…”