Morphological Control of InN Nanorods by Selective Area Growth–Hydride Vapor-Phase Epitaxy

Abstract

The control of the morphology of InN nanorods, which remains challenging due to complex mechanisms involved in the growth process, is essential for the next generation of nano-and optoelectronic devices. In this paper, we report on the Selective Area Growth (SAG) of InN nanorods on Ga-polar GaN/c-Al2O3 template using Hydride Vapor Phase Epitaxy (HVPE). A systematic study of the evolution of the shape of InN nanorods under various growth conditions: growth temperature, growth time and the input NH3 partial pressure, is carried out. The optimal growth temperature to achieve a perfect selectivity and prevent InN decomposition is first determined. The axial and radial growth rates dependence on the growth temperature and vapor phase composition with group V elements is discussed. The influence of mass transport on the InN nanorods geometry is shown to be more pronounced at extended growth time. The swapping of the nanorods morphology from pencil to a perfect hexagonal shape is controlled by varying the growth time. Photoluminescence measurements on InN nanorods are interpreted by considering a concentration of free electrons. The results reported herein provide relevant information for understanding SAG of InN, and could pave the way to develop high performance InN nanorods based devices.

Formation of voids in selective area growth of InN nanorods in SiNx on GaN templates

“…This may result in the void asymmetry, which is seen in Figure 2 (c). different conditions is presented elsewhere [30] . In brief, we found that the nanorods are unintentionally n-doped with a high electron concentration and PL peak energy is blue shifted when the diameter of nanorods decreases.…”

Comprehensive model toward optimization of SAG In-rich InGaN nanorods by hydride vapor phase epitaxy

“…Second, the average indium content x (determined by EDX on as-grown samples) in InGaN NRs can be tuned by the vapor phase composition, with lower r resulting in higher x. Third, the average length of the NRs increases with decreasing r. This result is expected from the growth rates of GaN and InN: InN growth rate is higher than GaN growth rate at given experimental parameters [31][32][33][34][35]. Fourth, NWs are present on the surface of the NRs, especially at their tips.…”

“…Solid III-V ternary alloys grow by incorporation of III-V binaries at different rates, GaN and InN in the present case [31][32][33][34][35]. InN and GaN binaries are grown by HVPE at very different temperatures, 610 °C-660 °C and 900 °C-1000 °C respectively.…”

“…This makes growth of InGaN alloys by HVPE quite difficult. Obviously, InGaN NRs must be grown at an intermediate temperature which should ensure a compromise between a good selectivity, crystal quality and InN stability [31,32]. After several experiments, the optimal growth temperature was selected at 660 °C.…”

Selective Area Growth of GaAs Nanowires and Microplatelet Arrays on Silicon by Hydride Vapor-Phase Epitaxy

“…Hydride vapor-phase epitaxy (HVPE) is a low-cost process known for its high intrinsic selectivity because of the low sticking coefficient of the III-chloride precursors on dielectric masks . In addition to specific growth kinetics, it has shown remarkable results on the selective epitaxy of III-nitride nanorods − and InAs NWs . The Au-catalyst-assisted synthesis of pure cubic zinc blende (ZB) GaAs NWs has been demonstrated by HVPE through the VLS process − , with a fast record growth rate .…”