Effects of carrier gas on the properties of InGaN/GaN quantum well structures grown by MOCVD

In this paper we report on the influence of the carrier gas used during growth on the optical and microstructural properties of In_xGa_1-xN/GaN multi-quantum well structures (L = 50 Å, x = 0.15) grown by MOCVD. The sample grown with hydrogen carrier gas resulted in a luminescence spectrum that consisted of a single line (FWHM = 57 meV) whereas growth of the barrier material using a nitrogen carrier gas results in luminescence spectra with FWHM in the range of 150 to 200 meV. The change in the optical properties correlates with changes in the microstructural properties. The inferior quality of the samples grown using nitrogen carrier gas is thought to be due to the increased density of growth nucleation sites formed during the growth process resulting in increased interface roughness and a progressive increase in the well thickness throughout the structures.