Interdiffusion of In and Ga in InGaN/GaN multiple quantum wells

Thermal stability of ${\mathrm{In}}_x{\mathrm{Ga}}_{\text{1-x}}\mathrm{N/GaN}$ multiple quantum wells with InN mole fraction of $\text{∼0.23}$ and $\text{∼0.30}$ was investigated by postgrowth thermal annealing. Low temperature photoluminescence spectroscopy was employed to determine the temperature dependence of the interdiffusion coefficient of In and Ga in InGaN/GaN quantum wells. The interdiffusion process is characterized by a single activation energy of about $\text{3.4±0.5\hspace{0.05em}}\mathrm{eV}$ and governed by vacancy-controlled second-nearest-neighbor hopping. Due to composition inhomogeneity, lower diffusivity is observed at the early stage of thermal annealing.