Growth and characterization of GePb/Ge multiple quantum wells

GePb/Ge multiple quantum well (MQW) structures with a Pb content of up to 7.2% were successfully grown on Ge(100) substrates via sputtering epitaxy. Scanning electron microscopy revealed that both the Pb content in the GePb layer and Ge layer thickness affect the Pb surface segregation. High-resolution X-ray diffraction and cross-sectional transmission electron microscopy indicated that the GePb/Ge MQW structures had a high crystal quality. Moreover, the thermal stability of the GePb/Ge MQW structures was investigated, and the MQW structures were found to be stable at an annealing temperature of 500 °C. The band gaps of the GePb/Ge MQWs were measured, and the band gap regulation caused by the quantum confinement effect was verified. These results indicate that the MQW structure is a promising approach for realizing efficient GePb light sources.