Porous pseudo-substrates for InGaN quantum well growth: Morphology, structure, and strain relaxation

0576333 - ÚFM 2024 RIV US eng J - Journal Article
Ji, Y. - Frentrup, M. - Zhang, X. - Pongrácz, Jakub - Fairclough, S. M. - Liu, Y. - Zhu, T. - Oliver, Rachel A.
Porous pseudo-substrates for InGaN quantum well growth: Morphology, structure, and strain relaxation.
Journal of Applied Physics. Roč. 134, č. 14 (2023), č. článku 145102. ISSN 0021-8979. E-ISSN 1089-7550
Institutional support: RVO:68081723
Keywords : InGaN * MQW * porosification * AFM * XRD * strain relaxation
OECD category: Condensed matter physics (including formerly solid state physics, supercond.)
Impact factor: 3.2, year: 2022
Method of publishing: Open access
https://pubs.aip.org/aip/jap/article/134/14/145102/2916034/Porous-pseudo-substrates-for-InGaN-quantum-well

Strain-related piezoelectric polarization is detrimental to the radiative recombination efficiency for InGaN-based long wavelength micro LEDs. In this paper, partial strain relaxation of InGaN multiple quantum wells (MQWs) on the wafer scale has been demonstrated by adopt ing a partially relaxed InGaN superlattice (SL) as the pseudo-substrate. Such a pseudo-substrate was obtained through an electro-chemical
etching method, in which a sub-surface InGaN/InGaN superlattice was etched via threading dislocations acting as etching channels. The
degree of strain relaxation in MQWs was studied by x-ray reciprocal space mapping, which shows an increase of the in-plane lattice constant
with the increase of etching voltage used in fabricating the pseudo-substrate. The reduced strain in the InGaN SL pseudo-substrate was dem onstrated to be transferable to InGaN MQWs grown on top of it, and the engineering of the degree of strain relaxation via porosification
was achieved. The highest relaxation degree of 44.7% was achieved in the sample with the porous InGaN SL template etched under the
highest etching voltage. Morphological and structural properties of partially relaxed InGaN MQWs samples were investigated with the com bination of atomic force and transmission electron microscopy. The increased porosity of the InGaN SL template and the newly formed
small V-pits during QW growth are suggested as possible origins for the increased strain relaxation of InGaN MQWs.
Permanent Link: https://hdl.handle.net/11104/0345962