Growth of one-dimensional Si/SiGe heterostructures by thermal CVD

Abstract

The first results on a simple new process for the direct fabrication of one-dimensional superlattices using common CVD chambers are presented. The experiments were carried out in a 200 mm industrial Centura reactor (Applied Materials).Low dimensionality and superlattices allow a significant increase in the figure of merit of thermoelectrics by controlling the transport of phonons and electrons. The monocrystalline nanowires produced according to this process are both one-dimensional and present heterostructures, with very thin layers (40 nm) of Si and SiGe. Concentrations up to 30 at.% Ge were obtained in the SiGe parts.Complementary techniques including transmission electronic microscopy (TEM), selected area electron diffraction (SAED), energy dispersive x-ray spectroscopy (EDS), scanning transmission electron microscopy (STEM) in bright field and high angle annular dark field (HAADF STEM), and energy-filtered transmission electron microscopy (EF-TEM) were used to characterize the nanoheterostructures.

Structural and optical properties of axial silicon-germanium nanowire heterojunctions

“…[35][36][37][38] It was shown that in lattice-mismatched NW HJs, structural relaxation can be associated with defects in the form of twin boundaries parallel to the growth axis and directly related to the NW kinking. 35 Also, a rough NW surface typically indicates a high density of surface defects, 39 and in many cases the NW diameter continuously decreases producing so-called "tapered" NWs.…”

Silicon Nanowires: A Review on Aspects of their Growth and their Electrical Properties

“…By switching the doping precursor, doping profiles in axial direction can be created. [19][20][21][22] REVIEW www.advmat.de…”

Interfacial abruptness in axial Si/SiGe heterostructures in nanowires probed by scanning capacitance microscopy

“…Moreover, high carrier mobility exhibited by SiGe promotes the performance of devices. Various methods employing laser ablation , plasma enhanced‐CVD , and thermal CVD have been illustrated in the literature for the elaboration of such heterostructures. In case of catalyzed growth of hNWs, while switching the fluxes of gases, the catalyst acts as a reservoir leading to a graded transition region from residual atoms present in the catalyst, over a certain length.…”