Spontaneous Ga incorporation in ZnO nanowires epitaxially grown on GaN substrate

Abstract

Surface‐diffusion‐induced spontaneous Ga incorporation process is demonstrated in ZnO nanowires grown on GaN substrate. Crucially, contrasting distributions of Ga atoms in axial and radial directions are experimentally observed. Ga atoms uniformly distribute along the ∼10 μm long ZnO nanowire and show a rapidly gradient distribution in the radial direction, which is attributed substantially to the difference between surface and volume diffusion. The understanding on the incorporation process can potentially modulate doping and properties in semiconductor nanomaterials. (© 2015 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)

Ga interaction with ZnO surfaces: Diffusion and melt-back etching

“…However, in the case of Ga-ZnO, the explanation based on our data is straightforward: The gallium droplets decompose ZnO and consume Zn underneath and, thus, sink into the whisker while continuously losing Ga because of its outdiffusion into the ZnO crystal. Supporting this conclusion, a spontaneous uptake of zinc by Gacontaining compounds has been reported earlier [19,28,29]. The dissolution of zinc in liquid Ga is possible even at very low temperatures, given a low eutectic point of the Ga-Zn melt [30].…”

p-GaN/n-ZnO Nanorod/CsPbBr3 Quantum Dots Decorated with ZnO Nanoseeds for Light-Emitting Diodes

“…As an important semiconductor material, zinc oxide (ZnO) possesses a broad band gap, and its band gap and lattice spacing are very close to those of GaN. − ZnO is also an intrinsic n-type material, so it can be employed as the n-type layer in an LED. In the last decades, many efforts have been made to realize ZnO-based thin-film LED devices, and most scientists studied the n-ZnO/p-GaN heterojunction LEDs. , Except for the traditional thin-film LED devices, ZnO can present many kinds of novel nanostructures, such as nanowires, − nanorods, , nanopins, and nanotubes, , and the ZnO nanodevices can demonstrate better light extraction and higher electroluminescent intensity. − Recently, Yang et al constructed blue-violet LEDs by covering solution-treated ZnO QDs with p-GaN/Mg . In the production of p-GaN/n-ZnO nanostructure LEDs, a ZnO nanoseed is usually necessary for ZnO nanorod growth.…”

Catalyst–substrate interaction and growth delay in vapor–liquid–solid nanowire growth

“…This mechanism thus renders a situation similar to the reservoir effect in the growth of segmented heteroepitaxial NWs [43], causing diluted interfaces. Consequently, unintentional NW doping by the substrate atoms may be introduced [19,20] or the NW growth direction is different than expected [18]. A growth delay is strongly dependent on the substrateinduced reservoir effect (see figure 4, inset).…”

“…The catalyst nanoparticle may dissolve substrate atoms during heating up to the growth temperature and, hence, significantly change the conditions for nucleation and subsequent growth. The uptake of substrate atoms by nanoparticles deposited on the substrate at elevated temperatures has been observed for different nanoparticle/substrate systems [12][13][14][15][16][17] and, in NW growth experiments, claimed to be responsible for changing the growth directions [18] or the optical properties of NWs [19,20] (due to incorporation of substrate atoms into the NW). Another important consequence of the substrate dissolution into the catalyst is a delayed NW growth, which is suspected to cause broad NW length distributions [21], thus making such NW arrays unsuitable for device fabrication.…”