In order to broaden the light emission of nitride quantum structures towards the red color, the technological problem of low In incorporation in InGaN−based heterostructures has to be solved. To overcome this problem superlattices grown on InGaN buffers with different In content were used. Based on the comparison of the calculated ab initio superlattice band gaps with the photoluminescence emission energies obtained from the measurements on the specially designed samples grown by metal-organic vapor phase epitaxy, it is shown that by changing the superlattice parameters and the composition of the buffer structures, the light emission can be shifted to lower energies by about 167 nm (0.72 eV) in comparison to the case of a similar type of superlattices grown on GaN substrate. The importance of using superlattices to achieve red emission and the critical role of the InGaN buffer are demonstrated.
The names of the individual files correspond to the numbering of the figures in the paper Staszczak, G.; Gorczyca, I.; Grzanka, E.; Smalc-Koziorowska, J.; Targowski, G.; Suski, T. Toward Red Light Emitters Based on InGaN-Containing Short-Period Superlattices with InGaN Buffers. Materials 2023, 16, 7386. https://doi.org/10.3390/ma16237386.
Files included in this collection:
Fig1 - Scheme of the calculated mInxGa1−xN/nInyGa1−yN SLs grown on thick buffer layer. QW layers are in red, and the QB layers are in blue color.
Fig2a, 2b, 2c - Calculated band gaps, Eg, vs. number of barrier MLs, n, for a set of SLs: (a) mIn0.33Ga0.67N/nGaN, (b) mIn0.33Ga0.67N/nIn0.165Ga0.835N, (c) mIn0.33Ga0.67N/nIn0.25Ga0.75N.
Fig3 - Calculated band gap for In0.33Ga0.67N/nGaN, mIn0.33Ga0.67N/In0.165Ga0.835N, and mIn0.33Ga0.67N/nIn0.25Ga0.75N SLs vs. In content in a buffer.
Fig4 - Scheme of the investigated mInxGa1−xN/nInyGa1−yN superlattices grown on buffer layer with z~0.17, and z~0.2 of In content; m, n denotes the number of QW and QB MLs, respectively. The thickness of one ML is around 0.26 nm.
Fig5a, 5b - The XRD patterns depict the characteristics of two samples: (a) sample A1 of InGaN/GaN SL (no indium in QBs), (b) sample A3 of InGaN/InGaN SL (with 15% In in QBs).
Fig6a, 6b, 6c, 6d - Comparison of XRD reciprocal space maps around the asymmetric GaN (10–14) reflection for (a) sample A1 and (b) sample A3 with the corresponding structures grown on GaN (c,d).
Fig7 - Cross-sectional TEM image of the mInGaN/nInGaN SLs with m = 2 and n = 30 MLs grown on In0.17Ga0.72N buffer layer (sample A3).
Fig 8a, 8b - Comparison of PL spectra @20K of the selected InxGa1−xN/InyGa1−yN SLs: (a) sample A1 without indium in QBs (y = 0), (b) sample B1 with indium in QBs (y = 0.17).
Fig9a, 9b - Comparison of the calculated SL band gaps, Eg, and PL emission energies. For (a) SLs 33/0 on buffers: GaN and In0.165Ga0.835N (blue line). (b) SLs 33/16.5 (green line) and 33/25 (violet line) on buffers: GaN and In0.165Ga0.835N and In0.33Ga0.67N.
