Effect of Substrate Misorientation on the Structural and Optical Characteristics of In-Rich InGaAs/GaAsP Quantum Wells

Zhiwei Li,Lijun Wang,Li Qin,Jianwei Zhang,Yue Song,Yinli Zhou,Yugang Zeng,Yongqiang Ning

doi:10.3390/app11188639

Abstract

InGaAs quantum well (QW) lasers have attracted significant attention owing to their considerable potential for applications in optical communications; however, the relationship between the misorientation of the substrates used to grow InGaAs QWs and the structural and optical properties of QWs is still ambiguous. In this study, In-rich InGaAs/GaAsP single QWs were grown in the same run via metal organic chemical vapor deposition on GaAs (001) substrates misoriented by 0°, 2°, and 15° toward (111). The effects of substrate misorientation on the crystal quality and structural properties of InGaAs/GaAsP were investigated by X-ray diffraction and Raman spectroscopy. The 0° substrate exhibited the least lattice relaxation, and with increasing misorientation, the degree of lattice relaxation increased. The optical properties of the InGaAs/GaAsP QWs were investigated using temperature-dependent photoluminescence. An abnormal S-shaped variation of the peak energy and inverse evolution of the spectral bandwidth were observed at low temperatures for the 2° substrate, caused by the localization potentials due to the In-rich clusters. Surface morphology observations revealed that the growth mode varied with different miscuts. Based on the experimental results obtained in this study, a mechanism elucidating the effect of substrate miscuts on the structural and optical properties of QWs was proposed and verified.

Highlights

IntroductionPublisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations
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◦, the growth mode became a step-flow mode and the heterointerface smoothness was degraded as the substrate misorientation increased

Summary

Introduction

Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Long wavelength semiconductor laser diodes have been an important technology in recent years, because of their major role in optical communications [1]. These lasers emit at wavelengths near the infrared band, and the InGaAs material system has shown promise as an active layer candidate for realizing wavelengths beyond 1 μm. Because the large lattice mismatch between InGaAs and GaAs substrates limits the layer thickness and heterointerface smoothness, several studies have been performed to improve the interface roughness and crystal quality. Nagle et al improved the quality of the

Methods

Discussion

Conclusion