Effects of Asymmetric Quantum Wells on the Structural and Optical Properties of InGaN-Based Light-Emitting Diodes

Abstract

A metalorganic vapor phase epitaxy-grown InGaN/GaN multiple-quantum-well (MQW) with three graded-thickness wells (the first-grown well had the greatest width) near the n-GaN was used as the active layer of an LED. For LEDs with an asymmetric quantum well (AQW), high-resolution X-ray diffraction and transmission electron microscopic reveal that the modified MQWs with a reasonable crystalline quality were coherently strained on the underlying GaN epilayers without any relaxation. In addition, the slight increase of indium segregation in the LED with an AQW may be attributed to variations in indium contents experienced during epitaxial growth of the wide well-containing MQWs. By preventing the energetic electrons from accumulating at the topmost quantum well nearest the p-GaN, the presence of light intensity roll-off in the LED with an AQW is shifted to higher currents and the corresponding maximum light output power is increased with a ratio 7.9% higher than that of normal LEDs. Finally, similar emission wavelengths were observed in the electroluminescence spectra of both LEDs, suggesting that light emitted mostly from the top quantum wells (near the p-GaN) while the emissions from the AQW region were insignificant.

Optimal Silicon Doping Layers of Quantum Barriers in the Growth Sequence Forming Soft Confinement Potential of Eight-Period In0.2Ga0.8N/GaN Quantum Wells of Blue LEDs

“…Soft confinement potential profile implies that conduction and valence band offsets of QWs are not taken as sharp step functions, i.e., not rectangular confining potential. Smooth confining potentials can suppress the Auger recombination to a great extent and prevent accumulation of plenty carriers in the first several wells in the injection direction of InGaN/GaN QWs [22–24]. Smooth confining potential can also be made through a linear decrease of In composition along the growth direction of InGaN/GaN QWs.…”

Oscillation of Electron Mobility in V‐Shaped Double Quantum Well Structure Under Applied Electric Field

“…In recent years, there is considerable interest in the study of semiconductor quantum well (QW) structures having different shapes of confinement potentials, viz., square, parabolic, graded, V-shaped, inverse parabolic, triangular, etc., because of their applications in devices. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] The change in the potential profile of a quantum well affects the subband energy states. Therefore, it is possible to manipulate the electronic properties of the two-dimensional electron gas (2DEG) systems by suitably varying the shape of the confinement potential to improve the device characteristics.…”

“…In recent years, there is considerable interest in the study of semiconductor quantum well (QW) structures having different shapes of confinement potentials, viz., square, parabolic, graded, V‐shaped, inverse parabolic, triangular, etc., because of their applications in devices . The change in the potential profile of a quantum well affects the subband energy states.…”

Optical characteristics of GaAsSb alloy after rapid thermal annealing

“…Carrier localization is a common phenomenon in semiconductors, which has been widely observed in alloys such as AlGaN [10][11][12][13], InGaN [14][15][16], InGaNP [17][18][19] and GaAsSb [20]. The behavior of carrier localization can be explained in terms of the excitons localized by potential fluctuation in semiconductors.…”