Nonequilibrium Plasma Aerotaxy of In_xGa_1-xN Nanocrystals

Semiconductors that have high chemical resistance and photostability, tunable absorption/emission properties, and low toxicity are in high demand for solar energy conversion and solid-state light sources. The solid solution of indium nitride and gallium nitride (In_xGa_1-xN) is a promising material for such applications. The composition-dependent band gap of In_xGa_1-xN may allow for tuning of the optical properties to efficiently harvest solar irradiance or achieve light emission across the visible/near infrared range. In reality, there are synthetic challenges associated with homogeneous thin film In_xGa_1-xN. The miscibility gap and strain-induced threading dislocations in In_xGa_1-xN with intermediate <i>x</i> have largely prevented realization of full spectral tunability. Freestanding, spherical In_xGa_1-xN nanocrystals stand to exhibit superior tunability by taking advantage effects at the nanoscale. Strain relaxation and size purification effects may aid in dislocation-free nanocrystal growth. Deviation from the bulk phase diagram at nanoscale particle size may stabilize nanoparticles with overall composition in the bulk miscibility gap, due to the cost of additional surface energy associated with phase segregation. Besides, freestanding nanocrystals are highly flexible for use in various applications. Yet, In_xGa_1-xN nanocrystal synthesis is underexplored. In this presentation, the synthesis of In_xGa_1-xN nanocrystals by Nonequilibrium Plasma Aerotaxy will be discussed. By feeding aerosols of indium and gallium metal, generated by thermal evaporation, into a nitrogen-argon low pressure, RF plasma, nanoparticles of pure gallium nitride, pure indium nitride, and their solid solution were produced. The composition of the solid solution was tuned by adjusting the molar feed rate of the metal aerosols. Progress towards achieving monodisperse, photoluminescent In_xGa_1-xN nanocrystals with <i>x</i> = 0.5 will be presented.