Growth of heavily doped monocrystalline and polycrystalline SiGe-based quantum dot superlattices

Various SiGe-based Quantum Dot Superlattices (QDSLs) were grown using an industrial Chemical Vapor Deposition tool with the intent to develop efficient thermoelectric thin films at a large scale. We report first on the growth of monocrystalline SiGe-based QDSLs. We were able to control the SiGe spacer width and the sizes and densities of Ge dots. A vertical ordering behavior was observed for large dot structures, but not for those with the smallest dots (30–70 nm wide, 3 nm high). In situ B doping operated during growth led to hole densities of 5 × 1019 to 1 × 1020 cm− 3. We also report on the growth of polycrystalline SiGe-based QDSLs with the same equipment. We show in particular that vertically aligned Ge dots were formed in a similar way as in monocrystalline structures despite the presence of stacking faults and grain boundaries. A heavy p doping was also obtained on some of these structures.

► Various SiGe-based Quantum Dot Superlattices are grown by chemical vapor deposition. ► Monocrystalline and polycrystalline structures were elaborated. ► High hole densities were obtained by in situ B doping on both kinds of structure. ► Vertical correlation phenomenon is evidenced on both kinds of structure.