Red Emission of InGaN/GaN Multiple‐Quantum‐Well Light‐Emitting Diode Structures with Indium‐Rich Clusters

Abstract

The authors present the growth of InGaN/GaN multiple-quantum-well (MQW) light-emitting diode (LED) structures, which show red emission. Transmission electron microscopy analyses proved that shell-like and quantum-dot-like (QD-like) clusters are formed in the initial four InGaN quantum well layers due in part to the lattice mismatch. The introduction of dislocations near the interfaces and interiors of MQWs induced high indium compositions in the InGaN quantum well layers. The room temperature photoluminescence (PL) measurement shows that the structure can emit the green to red broad spectral luminesce with major and minor peaks at 630 and 550 nm due to fluctuation of indium compositions in MQWs. In an electroluminescence (EL) spectrum measurement, the red emissions are blue shifted in the wavelength range from 630 to 609 nm with an increase of the injected currents from 5 to 100 mA.

Near-IR emission of InGaN quasi-quantum dots on non-polar GaN nanowire structures

“…10a , in general, the MQW structure causes the incorporation of different indium amounts along the length of the nanowires, resulting in different wavelengths with the separation of various indium amounts. 38 In contrast, QP structures will not be affected by this indium separation because they are formed as nanostructures in a completely independent state. Moreover, the MQW structure contains many defects in the InGaN quantum well region, while the QP structures will be free from defects in the main quantum well region due to the two-step strain relaxation.…”

“…To the best of our knowledge, this is a new record value not reported in previous studies in a similar indium content and wavelength range. 27,[36][37][38] Typically, when the indium composition is increased in the In x Ga 1-x N material, the defect density is dramatically increased due to the indium impurity and the lattice mismatch between In x Ga 1-x N and GaN, which causes an increase in the FWHM. In particular, it is common to show a FWHM greater than ~ 100 nm over a wavelength of ~ 600 nm.…”

Recent progress in red light-emitting diodes by III-nitride materials

“…The composite InGaN/GaN structures were formed by phase-separation due to surface roughness of the underlying n-GaN layer; emission was at 610 nm [189]. QD-like clusters formed into InGaN QWs due to InGaN phase-separation, which indicated red emission at 620 nm at 20 mA [184]. The blueshift behavior was only 2 nm with current injection from 40 to 100 mA.…”

“…InGaN and reduce QCSE by strain relaxation compared to conventional QW structures. In general, the QD-active region provides superior advantages such as stronger quantum confinement [181−183], carrier localization [184,185], short radiative carrier lifetime [186],…”

Impact of Cone‐Shape‐Patterned Sapphire Substrate and Temperature on the Epitaxial Growth of p‐GaN via MOCVD

“…For these applications, the GaN layer was usually grown on sapphire and silicon substrates due to the high cost of GaN and silicon carbide (SiC) substrates. Conventional sapphire was used as the substrate for GaN‐based LEDs with a GaN or AlN buffer layer . Nevertheless, the GaN layer contains a high density of threading dislocations (TDs) in the range of 10 9 –10 10 cm −2 and biaxial thermal stress, ascribed to the large mismatch of the lattice constant (16%) and of the coefficient of thermal expansion (CTE) (27%) between GaN and sapphire.…”