Investigation of temperature and H₂ 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 degrees C to 400 degrees 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.