Growth of axial SiGe heterostructures in nanowires using pulsed laser deposition

Abstract

Axial heterojunctions between pure silicon and pure germanium in nanowires have been realized combining pulsed laser deposition, chemical vapor deposition and electron beam evaporation in a vapor-liquid-solid nanowire growth experiment using gold nanoparticles as catalyst for the 1D wire growth. Energy dispersive x-ray mappings and line scans show a compositional transition from pure silicon to pure germanium and vice versa with exponential and thus comparably sharp transition slopes. Based on these results not only Si-Ge heterojunctions seem to be possible using the vapor-liquid-solid growth process but also heterojunctions in optoelectronic III-V compounds such as InGaAs/GaAs or group III nitride compounds such as InGaN/GaN as well as axial p-n junctions in Si nanowires.

Solvent Vapor Growth of Axial Heterostructure Nanowires with Multiple Alternating Segments of Silicon and Germanium

“…Efforts to include a third segment by reintroduction of Si monomers results in an alloy of Si/Ge as the terminating segment regardless of the type B catalyst used . This is consistent with many of the previous reports of axial Si/Ge hNW growth that consist of alternating Si and Si/Ge alloy segments formed by having a continuous flow of a Si source with the intermittent introduction of a Ge source to form the alloy segments. ,, These reports have mostly consisted of a Si segment first (Si–Ge) with very few reports of the reverse configuration, Ge–Si. ,, Also, reports of repeated alternating between pure Si and pure Ge segments in axial hNWs are very scarce with the only previous works on this showing quite short subsequent segments due to the slow VSS growth rates following the growth of an initial long Si segment under VLS conditions. , …”

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.…”

Self-assembled in-plane Ge nanowires on rib-patterned Si (1 1 10) templates

“…Nevertheless, in our work, the width of the prism-shaped Ge nanowire is merely about 12-15 nm, and thus their height is just about 0.84-1.05 nm, due to the fixed sidewall angle of 7.97°. Such a small cross section 075308-2 makes observation very difficult even with transmission electron microscopy (TEM) combined with energy dispersive x-ray (EDX) analysis, although this technique is rather a powerful tool in the recent studies on SiGe colloidal core-shell nanocrystals [30] and nanowires [31]. Thus, in this paper, we generally follow the strategy that has been successfully applied in our previous paper [22].…”