GaAs nanowires and related prismatic heterostructures

Abstract

The growth of GaAs nanowires by the gallium-assisted method with molecular beam epitaxy (MBE) is presented in this review article. The structure of the grown nanowires was investigated by means of scanning and transmission electron microscopy as well as Raman spectroscopy. Their optical properties were revealed by performing photoluminescence measurements at the single nanowire level. Furthermore, by tuning the MBE conditions to planar growth, quantum heterostructures on the side facets of the nanowires were achieved. High-resolution transmission electron microscopy proved that the grown heterostructures have epitaxial precision, while photoluminescence measurements showed that they possess excellent optical quality. These quantum heterostructures constitute templates for developing novel nanowire based devices, such as a high electron mobility one-dimensional transistor or third generation solar cells.

Position-Controlled Uniform GaAs Nanowires on Silicon using Nanoimprint Lithography

“…However, the NWs will then contain a high density of twin defects in the ZB part and/or small WZ inclusions with SFs. In fact, the existing reports on self-catalyzed GaAs NWs in the literature either do not comment on the crystal phase [56], or the NWs contain crystal defects (twins or SFs) as observed in this study [109,190]. However, as the full analysis of the results from this optical property optimization study is under process (Paper VIII, in preparation), it is not included in this thesis.…”

“…However, usually a lower growth temperature is used in the literature [67]. Moreover, the optical quality of radial GaAs shell grown on the side-facets of NWs at low temperature in GaAs/AlGaAs multi-quantum well structures, was reported to have a superior optical quality as compared to those grown at high temperature [190,199]. Therefore the effect of Be-doped GaAs shells grown at 460 °C on the optical quality should be further studied.…”

Raman spectroscopy of GaP/GaNP core/shell nanowires

“…19,20 An effective technique that allows non-destructive characterization of electronic and structural properties of nanoscale materials is micro-Raman spectroscopy. This technique has been applied to several III-V NW systems [19][20][21][22][23][24][25][26][27] and provided important information regarding crystalline structure, such as presence of staking disorder and formation of alternating zinc-blende (ZB)/wurtzite (WZ) (ZB/WZ) polytypes, strain as well as diameter modulations. The purpose of this work is by using Raman spectroscopy to characterize structural and phonon properties of recently developed coaxial GaP/GaNP NWs that are currently unknown.…”

InP–InxGa1−xAs core-multi-shell nanowire quantum wells with tunable emission in the 1.3–1.55 μm wavelength range

“…Note that 7 at 300 K, whereas a very weak signal is observed at 77 K. This shows that the quantum well is highly efficient in capturing carriers, almost completely avoiding recombination in the InP core or outer barrier. This is one of the main differences and advantages of the current material system compared to the more commonly reported GaAs-AlGaAs nanowire QWs, where emission by the nanowire core is almost always visible and in most cases stronger than the GaAs QW emission [38][39][40] due to the presence of GaAs nanowire core, which has the lowest energy gap, hence forming the most preferred recombination location in the structure. The bright emission observed at room temperature and 77 K also indicates that there is no significant effect of the stacking faults observed along the nanowire on the PL efficiency.…”

“…In some cases, although not seen in the current study, relatively high level of broadening and multiple sharp peaks can be observed for very thin QWs due to higher sensitivity to mono-layer fluctuations and quantum dot-like formations. 18,38,39 Electron capture efficiency could also be low for very thin QWs. Varying emission wavelength by tuning the QW alloy composition minimises these limitations at very small and large thicknesses, albeit at the possible expense of formation of dislocations due to lattice mismatch.…”