Growth mechanism of catalyst- and template-free group III-nitride nanorods
نویسندگان
چکیده
A feasible mechanism for catalystand template-free group III-nitride nanorod growth by hydride vapor phase epitaxy (HVPE) is proposed. The mechanism is composed of random nanoparticle nucleation from growth conditions—growth temperature and Cl/group III ratio—based on the proposed mechanism, and the computed values showed good agreement with reported experimental results. The involvement of a group III trichloride as a key species in the proposed mechanism required the Cl/group III ratio to be 3 according to stoichiometry. A higher Cl/group III ratio led to etching of the solid phase and a lower ratio favored two-dimensional film growth instead. The zone of GaN and InN nanorod growth by HVPE was shown to lie in the vicinity of the growth–etch transition. A two-temperature approach, employed in GaN nanorod growth, was supported by the deconvolution of two conflicting kinetic and thermodynamic constraints in terms of growth temperature: a high-temperature region for GaCl3 formation that is kinetically limited at low temperature and a low-temperature region for GaN nanorod growth without GaN etching that is thermodynamically favorable in a chlorinated environment at high temperature. The temperature for AlN nanorod growth by chemical vapor deposition using AlCl3 and NH3 was limited only by the thermodynamic constraint of ammonia adduct (Cl3Al:NH3) formation. & 2008 Elsevier B.V. All rights reserved.
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