Polarity Control in Growing Highly Ga-Doped ZnO Nanowires with the Vapor–Liquid–Solid Process

Abstract

Surface behavior modification by forming surface-transparent conductive nanowires (NWs) is an important technique for many applications, particularly when the polarities of the NWs can be controlled. The polarities of Ga-doped ZnO (GaZnO) NWs grown on templates of different polarities under different growth conditions are studied for exploring a polarity control growth technique. The NWs are formed on Ga- and N-face GaN through the vapor–liquid–solid (VLS) process using Ag nanoparticles as growth catalyst. The NWs grown on templates of different polarities under the Zn- (O-) rich conditions are always Zn (O) polar. During the early stage of NW growth, because the lattice sizes among different nucleation islands formed at the triple-phase line are quite different, high-density planar defects are produced when lateral growths from multiple nucleation islands form a GaZnO double bilayer. In this situation, frequent domain inversions occur, and GaZnO polarity is unstable. Under the Zn- (O-) rich conditions, because the lateral growth rate of GaZnO in the Zn- (O-) polar structure is higher due to more available dangling bonds, the growth of the Zn- (O-) polar structure dominates NW formation such that the NW eventually becomes Zn (O) polar irrespective of the polarity of the growth template. Therefore, the polarity of a doped-ZnO NW can be controlled simply by the relative supply rates of Zn and O during VLS growth.

The Effect of the Solution Flow and Electrical Field on the Homogeneity of Large-Scale Electrodeposited ZnO Nanorods

“…In order to realize practical application, deposition at a large scale is necessary and valuable, paving the way for the industrialized production of ZnO NR ARCs. For production, various methods have been employed to prepare ZnO NRs, for example, chemical vapor deposition [ 28 , 29 ], the vapor transport method [ 30 ], thermal evaporation [ 31 ], and the vapor–liquid–solid technique [ 32 ]. Compared to these methods, electrodeposition is simpler and more compatible with low-temperature substrates due to its moderate operating temperature [ 33 , 34 , 35 , 36 , 37 , 38 ].…”

Growth of Vertical ZnO Nanorods from Patterned Films via Decomposition of Zinc Acetate by Focused Ion Beam: Implication for UV Detection

“…The vapor-phase approach, which includes CVD, vapor–liquid–solid, ,− and vapor–solid methods is frequently used for growing ZnO NRs without seed layers. However, these methods generally require high reaction temperatures.…”

Highly-Conductive, Transparent Ga-Doped ZnO Nanoneedles for Improving the Efficiencies of GaN Light-Emitting Diode and Si Solar Cell

“…Recently, the growth of highly-conductive Ga-doped (5-6% in doping concentration) ZnO (GaZnO) nanoneedles (NNs) based on the vapor-liquid-solid (VLS) process with molecular beam epitaxy (MBE) by using Ag nanoparticles (NPs) as catalyst has been demonstrated. [6][7][8] The crystallographic structures of the grown GaZnO NNs have also been well studied. 7,8 With the Ag NP size in the range of 10-20 nm, GaZnO NNs can be formed only when the growth temperature is higher than 350°C, above which at least part of an Ag NP can be melted for serving as the VLS catalyst.…”

“…[6][7][8] The crystallographic structures of the grown GaZnO NNs have also been well studied. 7,8 With the Ag NP size in the range of 10-20 nm, GaZnO NNs can be formed only when the growth temperature is higher than 350°C, above which at least part of an Ag NP can be melted for serving as the VLS catalyst. At this growth temperature, residual Ag NPs of a lower density can be found around the NN bottom, which are covered by a simultaneously grown GaZnO thin film.…”