Light emission enhancement in blue InGaAlN/InGaN quantum well structures

Abstract

Optical properties of blue AlInGaN/InGaN quantum well (QW) structures with a quaternary AlInGaN well layer were investigated by using the non-Markovian gain model with many-body effects. The band-gap expression of the AlInGaN materials was determined through a comparison with experimental results. We found that the emission peak can be enhanced by using quaternary AlInGaN well and is sensitive on In composition in the InGaN barrier. For example, the spontaneous emission coefficient for Al0.08In0.22Ga0.67 N/InxGa1−xN QW structures shows a maximum at In composition of 0.13 in the barrier and gradually decreases with increasing In composition. This is attributed to the fact that the quasi-Fermi-level separation linearly decreases with increasing In composition in the barrier due to the decrease in the conduction and valence band offsets. The AlInGaN/InGaN system with zero internal field is found to have smaller emission peak than the AlInGaN/InGaN system with nonzero internal field due to smaller band offsets.

Relaxation and critical strain for maximum In incorporation in AlInGaN on GaN grown by metal organic vapour phase epitaxy

“…5,6 This offers unique opportunities for polarization-engineered nitride heterostructures, like enhancement-mode HEMT or LED structures without emission wavelength shift. [7][8][9][10][11] In this work, we investigate the influence of deposition conditions on the composition and structural properties of AlInGaN. Especially, to understand polarization effects in nitride heterostructures, a deeper comprehension of strain and relaxation in these layers is necessary.…”

Quaternary AlInGaN/InGaN quantum well on vicinal c-plane substrate for high emission intensity of green wavelengths

“…9,26,35,36 The In composition in the AlInGaN well layer to give zero internal field is shown to increase with increasing the In composition in InGaN barrier. Thus, in the case of the QW structure with green wavelength regime, the QW structure with a relatively higher In composition in the InGaN barrier is needed to obtain a zero internal field.…”

“…In the case of c-plane, AlInGaN-based QW structures are shown to be possible for high intensity optoelectronic devices at blue and shorter wavelengths. [9][10][11][12] On the experimental side, several groups [13][14][15][16][17] have studied semi-polar InGaN/GaN QW structures. For example, semipolar planes such as the (20 21) plane, which is miscut by 15 from the m-plane (75 from the c-plane), have attracted significant interest due to their promising performance in the green region of the spectrum.…”

Performance Enhancement of Ultraviolet Light-Emitting Diodes by Incorporating a Thin Al(In)GaN Interlayer in Multiquantum-Well Region

“…The surface roughness can be further improved by using a graded AlInGaN interlayer (LED-C), which is mainly owing to the addition of indium as a surfactant into the AlGaN [23], [26]. In addition, AlInGaN layers have some advantages, such as In-segregation effect and reduced lattice mismatch with a lower internal field [8]. Thus, a good MQW quality with better IQE can be obtained by using the AlInGaN interlayer.…”

“…Therefore, how to improve the overall efficiency is an important issue for the fabrication of high-efficiency UV-LEDs. Recently, in order to increase the carrier confinement for the UV-LEDs, several approaches have been successfully proposed, such as electron block layer (EBL) with different growth processes [4]- [7] and Al(In)GaN/InGaN multi-quantum-wells (MQWs) [8]- [11]. On the other hand, various techniques have been developed to reduce the dislocation density and self-absorption, including air-void structure [12], patterned sapphire substrate (PSS) [13], epitaxial lateral overgrowth (ELOG) [14], AlN/GaN template [15], nonpolar-GaN [16], and quantum dot/wire/well hybrid LEDs [17].…”