Importance of growth temperature on achieving lattice-matched and strained InAlN/GaN heterostructure by plasma-assisted molecular beam epitaxy

Abstract

We investigate the role of growth temperature on the optimization of lattice-matched In0.17Al0.83N/GaN heterostructure and its structural evolutions along with electrical transport studies. The indium content gradually reduces with the increase of growth temperature and approaches lattice-matched with GaN having very smooth and high structural quality at 450°C. The InAlN layers grown at high growth temperature (480°C) retain very low Indium content of ∼ 4 % in which cracks are mushroomed due to tensile strain while above lattice matched (>17%) layers maintain crack-free compressive strain nature. The near lattice-matched heterostructure demonstrate a strong carrier confinement with very high two-dimensional sheet carrier density of ∼2.9 × 1013 cm-2 with the sheet resistance of ∼450 Ω/□ at room temperature as due to the manifestation of spontaneous polarization charge differences between InAlN and GaN layers.