MBE growth and characterization of strained GeSn/Ge multiple quantum well structures
Nirosh M. Eldose, Fernando M. de Oliveira, Serhii Kryvyi, Hryhorii Stanchu, Dinesh Baral, Diandian Zhang, Shang Liu, Yi‐Cheng Wang, Jifeng Liu, Mourad Benamara, Mohammad Zamani‐Alavijeh, Ilias Bikmukhametov, Yuriy I. Mazur, Wei Du, Shui-Qing Yu, Gregory J. Salamo
Abstract
Abstract Germanium tin (GeSn) alloys have emerged as pivotal materials for advanced optoelectronic applications owing to their tunable bandgaps and compatibility with silicon-based technologies. In this study, high quality GeSn multiple quantum wells (MQWs) with Sn concentrations of 7.0 ± 0.5% and 7.7 ± 0.5% were successfully grown on Ge(001) substrates using molecular beam epitaxy (MBE). The pseudomorphic growth of the MQWs and the high crystalline quality is evidenced by high-resolution x-ray diffraction. Cross-sectional transmission electron microscopy confirms a low defect density at the interfaces between GeSn wells and Ge barriers. Atomic probe topography shows the consumption of Sn atoms in the Ge barrier layer, preventing Sn segregation through the MQW structure. Atomic force microscopy reveals a smooth surface free of Sn droplets. Photoluminescence spectroscopy demonstrates optical emission at different wavelengths for varying Sn composition and QW thickness, confirming quantum confinement effects. These findings highlight the potential of MBE to produce high-quality GeSn/Ge MQWs with minimal defects, offering significant contribution for the next generation of optoelectronic devices.