## 4 Conclusions  
The effect of substrate misorientation on the structure and optical properties of In-rich InGaAs/GaAs QW structures grown via MOCVD was investigated. Results obtained via XRD and Raman spectroscopy indicated that the strain in the InGaAs/GaAsP decreased monotonically with increasing misorientation. AFM was used to probe the surface morphology and microstructures of the samples, which revealed that with a substrate misorientation of \(0^{\circ}\), the growth mode became a step-flow mode and the heterointerface smoothness was degraded as the substrate misorientation increased. The growth mode transformed into three-dimensional growth as the substrate misorientation increased to \(15^{\circ}\). Based on these results, the growth of the InGaAs/GaAsP QW nanostructures was modeled from the viewpoint of atomic step motion; a mechanism associated with the accumulation of In on tilted substrates was proposed and verified. The localization potentials formed by the In clusters were primarily caused by the appropriate misoriented substrates and the preferential of In/Ga atoms on the terrace to the steps. Based on these results and the parameters related to the temperature-dependent photoluminescence of the samples, the strain relaxation degree of \(0^{\circ}\) substrate is the minimum due to the absence of a high density of step edges, a mechanism was proposed for the S-shaped temperature dependence of the peak energy and FWHM of the \(2^{\circ}\) sample. Partial strain relaxation occurs with the formation of in clusters owing to the relatively narrow steps, when the substrate misorientation increases to \(15^{\circ}\), the formation of randomly positioned growth nuclei yield substantial strain relaxation. Conceptualization, Z.L. and Y.Z. ([PERSON]); methodology, Z.L. and Y.Z. ([PERSON]); software, Z.L. ; validation, Y.N., Y.Z. ([PERSON]) and Y.S. ; formal analysis, J.Z. ; investigation, Z.L. ; resources, Y.N. ; data curation, Y.Z. ([PERSON]); writing--original draft preparation, Z.L. ; writing--review and editing, Y.Z. ([PERSON]) and Y.S. ; visualization, Y.S. and L.Q. ; supervision, Y.N. ; project administration, Y.N. and L.W. ; funding acquisition, Y.S. and L.Q. All authors have read and agreed to the published version of the manuscript. Figure 11: Temperature dependence of PL integrated intensities of the InGaAs/GaAsP QWs on substrates misoriented by (**a**) \(0^{\circ}\), (**b**) \(2^{\circ}\), and (**c**) \(15^{\circ}\); the data are fitted using the Arrhenius model. An abnormal temperature-dependent PL intensity is observed in the sample with the \(2^{\circ}\)-misoriented substrate. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Sample** & \(\mathbf{C_{1}}\) & \(\mathbf{E_{A}}\) **(meV)** & \(\mathbf{C_{2}}\) & \(\mathbf{E_{B}}\) **(meV)** \\ \hline \(0^{\circ}\) & 5.30 & 21.72 & 260 & 106.55 \\ \(2^{\circ}\) & 4.01 & 35.25 & 1100 & 148.47 \\ \(15^{\circ}\) & 5.96 & 18.72 & 1525 & 87.26 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Parameters obtained by fitting the Arrhenius model for data representing samples with differently misoriented substrates. **Funding:** This research was funded by National Natural Science Foundation of China (NSFC) (61904179, 62090060, 61727822, 61991433, 61604151, 11874353, 61935009, 61934003, 61674148, 61805236); National Science and Technology Major Project of China (2018 YFB2200300, 2016 YFE0200700, 2017 YFB0503100, 2017 YFB0405100, 2018 YFB0504600); CAS Projection of instrument development (YJKYYQ20180045); Frontier Science Key Program of the President of the Chinese Academy of Sciences (QYZDY-SSW-JSC006); Key R & D projects in Guangdong Province (2020B090922003); Equipment pre research (41414060103); Pilot project of CAS (XDB43030302); Science and Technology Development Project of Jilin Province (20200401069 GX, 20200401062 GX, 20190302042 GX). **Institutional Review Board Statement:** Not applicable. **Informed Consent Statement:** Not applicable.