Green to blue polarization compensated c-axis oriented multi-quantum wells by AlGaInN barrier layers

Abstract

We report on an over 50% reduction in polarization field strength in c-axis oriented InGaN multi-quantum wells (MQW) by applying quaternary AlGaInN barrier layers with better polarization matching to InGaN than GaN barriers. With the reduction in polarization fields, a strong blue-shift in photoluminescence is observed in agreement with theoretical expectation and simulations. By gracing incidence x-ray diffraction measurements, we demonstrate that partial relaxation already occurs for GaN/InGaN MQWs. As a consequence, the requirement of higher In-content layers for green light emission is in conflict with increasing strain leading to lattice relaxation.

Polarization engineering of c‐plane InGaN quantum wells by pulsed‐flow growth of AlInGaN barriers

“…In sample series A (Fig. (a)) the PL peak position of the MQW emission shifts from 580 to 490 nm (∼393 meV) for samples A0–A4 and is comparable to the luminescence shift found in our previous work . Samples A2 and A4 exhibit an additional PL signal at 408 nm (3.039 eV) and 450 nm (2.755 eV), respectively.…”

“…In the past, we have reported on the growth as well as on structural and optical characterization of InGaN MQW structures with partial reduction of the polarization mismatch by use of quaternary AlInGaN barriers . Our experiments employing continuous layer growth indicated at low growth rates a possibly higher stability of highly lattice‐mismatched AlInGaN layers against lattice relaxation, a key requirement for the realization of polarization‐field reduced InGaN/AlInGaN QWs emitting in the green spectral region.…”

Investigating the Effect of Piezoelectric Polarization on GaN-Based LEDs with Different Prestrain Layer by Temperature-Dependent Electroluminescence

“…This inherent effect, which was called quantum-confined stark effect (QCSE), has resulted in the reduction of quantum efficiency for the GaN-based LEDs. This is because the QCSE within MQWs region lead to the significant spatial separation of the electron and hole wave functions and the reduction of the electron-hole recombination probability [1][2][3][4][5]. Furthermore, investigating the spontaneous and piezoelectric polarization-induced electrostatic field on InGaN/GaN MQWs heterostructure is a very important key issue currently.…”

Numerical study of the suppressed efficiency droop in blue InGaN LEDs with polarization-matched configuration

“…A recent report indicated that, with increasing indium content in the AlGaInN barriers, an increasing pit and defect density is observed, and more lattice relaxation is determined [22]. Although the technology in growing AlGaInN films is still under development, some approaches regarding the polarization-matched active region have been achieved in experiments, which demonstrates its possibility for future applications [22,23]. Note that other approaches, such as reducing GaN barrier thickness and growing semipolar or nonpolar LEDs, might also be of great help in solving the problem of efficiency droop [24][25][26].…”

“…The increased strain accumulation in the active region makes it a great challenge to grow high-crystalline-quality devices. A recent report indicated that, with increasing indium content in the AlGaInN barriers, an increasing pit and defect density is observed, and more lattice relaxation is determined [22]. Although the technology in growing AlGaInN films is still under development, some approaches regarding the polarization-matched active region have been achieved in experiments, which demonstrates its possibility for future applications [22,23].…”