GaAs free-standing quantum-size wires

Abstract

Ultrathin GaAs wires as thin as 15–40 nm and about 2 μm long have been grown on a GaAs substrate by metal-organic vapor-phase epitaxy. The wires, which consist of whiskers, are grown between 380 and 550 °C using trimethylgallium and arsine (AsH3) as source materials. It is found that the wire growth direction is parallel to the [111] arsenic dangling-bond direction and can be perfectly controlled by the crystallographic orientation of the GaAs substrate surface. From transmission electron microscopic analysis it is revealed that the crystal structure of the wire coincides with the zinc-blende type for the growth temperature range of 460–500 °C, but it changes to the wurtzite type at 420 °C and temperatures higher than 500 °C. It is also found that the wires have a twin-type structure around the [111] growth axis for zinc blende and [0001] growth axis for wurtzite. Photoluminescence study of these wires shows that the luminescence peak energy shifts to a higher energy as the wire width decreases from 100 to about 35 nm. In terms of luminescence polarization it is confirmed that the luminescence intensity parallel to the wires is four times greater than that perpendicular to the wires. These results clearly indicate the quantum-size effect of carriers confined in the wire. As a preliminary application to devices, a p-n junction has been formed along the GaAs wire. Light emission by current injection to the p-n junction wires has been observed in continuous operation at room temperature.

Influence of the (111) twinning on the formation of diamond cubic/diamond hexagonal heterostructures in Cu-catalyzed Si nanowires

“…Nevertheless, just four of them have been found to remain stable or metastable at ambient: Si I, a-Si, Si III, and Si IV, the first two being classical device materials. 57 Hiruma et al 58 attributed the density of growth twins in GaAs NWs to the competing stabilities of the zinc-blende and wurtzite polytypic forms of this compound. Attending to these considerations, the mere existence of ͗111͘ twins in our Si NWs should lead to the formation of local diamond hexagonal regions such as it has been found, see Fig.…”

Scanning gate imaging of quantum dots in 1D ultra-thin InAs/InP nanowires

“…One-dimensional (1D) semiconductor nanostructures, such as nanowires [1][2][3][4][5][6][7][8], carbon nanotubes [9][10][11][12], and cleaved-edge overgrowth wires [13][14][15][16], offer the opportunity to investigate interesting electronic phenomena in 1D. Select quantum mechanical effects that are not present or vastly more complicated in higher dimensional systems can be explored.…”

Realization of conductive InAs nanotubes based on lattice-mismatched InP∕InAs core-shell nanowires

“…In the present work, we employed the catalyst-free selective area metalorganic vapor phase epitaxy ͑SA-MOVPE͒ which is a totally different approach to the conventional metal-catalyst assisted VLS growth technique by which most of the nanowires are grown. 12 The advantages of SA-MOVPE are that the nanowires can be grown without the use of a seed particle and their size, shape, and position can be precisely controlled. [13][14][15] Also, nanotubes realized from core-shell nanowires grown by SA-MOVPE will be of superior crystal- line quality as both the core and the shell are grown by pure epitaxial method and the catalyst-free, single-step growth will reduce defects and other unwanted impurity incorporation.…”