InSb epilayers and quantum wells grown on Ge(001) substrates by MBE

For digital logic applications, transistors with both electron and hole channels are required. InSb:Ge heterostructure is an ideal material since the highest carrier mobilities for n and p-type quantum wells (QWs) are observed in InSb and Ge channels, respectively. We report on the MBE growth of InSb-based materials on Ge(001) substrates. A temperature variation two-step growth procedure (TSGP) is more effective than direct growth of InSb on Ge(001). In the TSGP, an initial 100-nm InSb layer was grown at a temperature of 340$^{o}$C before increasing the substrate temperature to 420$^{o}$C for the rest of the growth. The initial growth forms a wetting layer that minimizes defects at the InSb/Ge interface. The X-ray rocking curve width of a 5.0-$\mu $m-thick InSb epilayer is 173 arc sec. Electron mobilities of a 5.0-$\mu $m-thick InSb epilayer and an InSb/Al$_{0.20}$In$_{0.80}$Sb QW at room temperature are 34,500 and 8,600 cm$^{2}$/V-s, respectively. These are the highest mobilities for an InSb epilayer and QW on Ge(001) substrates reported so far. This work was supported by NSF Grant DMR-0520550 and OCAST contract AR071-025.