Effects of Zn Doping on the Surface Structure and Initial Growth Processes of InP Thin Film Layers on InP(111)B Substrate

Abstract

The effects of Zn atoms as a dopant on the surface structure and initial growth processes on InP(111)B substrate are theoretically investigated on the basis of surface phase diagrams which are obtained by comparing the adsorption energy given by ab initio calculations with the gas-phase chemical potentials. The calculated surface phase diagrams demonstrate that the Zn-incorporated surface is stabilized under the growth conditions with high Zn supply ratio. Furthermore, In atoms tend to easily adsorb on the Zn-incorporated surface as an In-P dimer due to the formation of Zn-P and P-P bonds, implying that the adsorption of In atoms and resultant growth processes are promoted on the Zn-incorporated InP(111)B surface which is stabilized under Zn-rich conditions. These results suggest that effects of Zn doping on the surface structure and initial growth processes are crucial for understanding the bidirectional growth mechanisms of InP nanowires on InP(111)B substrate.

High-Yield Growth and Characterization of ⟨100⟩ InP p–n Diode Nanowires

“…In particular, it is important to point out the influence of Zn on γ SV , which has not been considered extensively before. It has already been demonstrated that DEZn can modify the surface of InP substrates, thus affecting γ SV ; , in our case, we expect DEZn to destabilize the catalyst, in particular by increasing its wetting and resulting in a smaller contact angle, by modifying the termination of the (100) InP substrate. There are two contrasting mechanisms expected to act on the catalyst: the first, crucial at high [DEZn], promotes high vertical yield by increasing the catalyst volume and thus the contact angle and affecting the liquid–vapor and liquid–solid interfaces.…”

Exploring the Internal Radiative Efficiency of Selective Area Nanowires

“…The PL intensity in this case is influenced mainly by a modification in the density of point defects, such as the introduction of P vacancies [27], which are included because of the increased evaporation of precursors and change in the surface reconstruction of the nanowire top surface, which are both expected with rising temperature [28]. Radiative recombination is then reduced at extremely high temperature by the accumulation of point defects.…”

“…Even if it is not incorporated in the bulk of the nanowires, it can still accumulate at the surface of the nanowire lateral facets, where it would heavily increase the surface recombination. A possible explanation for the different incorporation of Zn on the top surface (where the axial growth takes place) and the lateral facets (where no radial growth is observed) is explained by the fact that lateral facets have different crystalline orientations, which result in a dissimilar Zn atom adsorption [28]. The adsorption is not influenced by an increased DEZn molar fraction, as even at the lowest flow there would be an excess of Zn atoms.…”