Electronic and optical properties of staggered InGaN/InGaN quantum‐well light‐emitting diodes

Abstract

Electronic and optical properties of 440 and 530 nm staggered InGaN/InGaN/GaN quantum‐well (QW) light‐emitting diodes are investigated using the multiband effective‐mass theory. These results are compared with those of conventional InGaN/GaN QW structures. The staggered QW structure requires a slightly larger In composition than the conventional QW structure to obtain a given wavelength. The spontaneous emission is found to be improved with the inclusion of the staggered layer for QW structures with a relatively thick well width and the longer wavelength (λ = 530 nm). On the other hand, in the case of QW structures with a relatively thin well width (Lw = 2 nm), the spontaneous emission peak is almost unaffected by a staggered layer.

Cathodoluminescence characteristics of linearly shaped staggered InGaN quantum wells light-emitting diodes

“…Previously, the concepts of the 2-layer staggered and 3-layer staggered InGaN QWs lead to significant enhancement on the electron-hole wavefunction overlap (Γ e_hh ) as compared to that of the conventional InGaN QW [27][28][29][30][31][32][33][34][35][36][37]. The enhanced optical matrix element in staggered InGaN QWs has led to 2.5-3.5 times increase in radiative recombination rate and radiative efficiency for 520-525 nm emitting nitride LEDs [27][28][29][30][31][32][33][34][35][36][37].…”

“…The charge separation reduces the electron-hole wavefunction overlap (Γ e_hh ) in InGaN QW, which leads to significant reduction in its radiative recombination rate (~ | Γ e_hh | 2 ). Several approaches have been proposed to enhance the overlap Γ e_hh such as 1) non-polar InGaN QW [24], 2) InGaN QW with δ-AlGaN layer [25,26], 3) staggered InGaN QW [27][28][29][30][31][32][33][34][35][36][37], 4) type-II InGaN-GaNAs QW [38][39][40], and 5) strain-compensated InGaNAlGaN QW [41,42].…”

“…The enhanced optical matrix element in staggered InGaN QWs has led to 2.5-3.5 times increase in radiative recombination rate and radiative efficiency for 520-525 nm emitting nitride LEDs [27][28][29][30][31][32][33][34][35][36][37]. The use of 3-layer staggered InGaN QW with high-In InGaN layer in the center and lower-In InGaN layers at the side [30][31][32][33] has shown that the introduction of potential minima in the center of the QW results in the shift of both electron and hole wavefunction toward the center of the QW region, which leads to significant enhancement in the electron-hole wavefunction overlap (Γ e_hh ) and spontaneous emission rate.…”

Theoretical studies on light emission characteristics of high-efficiency BInGaN/GaN quantum well structures with blue spectral range

“…For example, two-and three-layer staggered QW structures were studied by several authors [5e8]. However, it was pointed out that these structures are not effective in improving the light emission of the blue spectral regime [9,10]. Hence, another approach will be necessary to obtain blue optoelectronic devices with a high internal efficiency.…”

Surface plasmon dispersion engineering via double-metallic Au/Ag layers for nitride light-emitting diodes

“…Several approaches have been demonstrated to suppress the charge separation in polar InGaN QWs by employing novel QWs with improved electron-hole wave function overlap (Γ e_hh ), as follows 1) staggered InGaN QW [5][6][7][8][9][10][11][12][13][14], 2) type-II InGaN-GaNAs QW [15,16], 3) strain-compensated InGaN-AlGaN QW [17,18], 4) InGaN QW with embedded δ-AlGaN layer [19,20], and 5) triangular InGaN QW [21].…”