Investigation of temperature and H 2 on GePb/Ge multiple quantum well growth

To reveal the growth behavior of GePb/Ge multiple quantum well (MQW) samples, both the influence of growth temperature and H 2 /Ar atmosphere are investigated by sputtering epitaxy. As the growth temperature increases from 250 °C to 400 °C, Pb atoms become more active and migrate easily to the surface, forming Pb clusters. As a result, the Pb composition in the GePb/Ge MQW is decreased from 3.5% to 1.8%. When H 2 is introduced into the chamber, it is found that the MQW disappears and GePb film with uniform Pb distribution is formed. This is possibly because that the introduction of H 2 can retain Pb atoms and the GePb is still grown even if the Pb flux is off. The results show that low temperature and H 2 atmosphere are effective methods to further break the low solid solubility limit of Pb in Ge.