Growth of InAlGaN Quaternary Alloys by Pulsed Metalorganic Chemical Vapor Deposition

Epitaxial growth of InAlGaN/GaN structures are performed on the c-plane sapphire by pulsed metal organic chemical vapor deposition with different triethylgallium (TEGa) flows in the growth process of InAlGaN quaternary alloys. X-ray photoelectron spectroscopy results show that the Al/In ratio of the samples increases as the TEGa flows increase in the InAlGaN quaternary growth process. High-resolution x-ray diffraction results show that the crystal quality is improved with increasing TEGa flows. Morphology of the InAlGaN/GaN heterostructures is characterized by an atomic force microscopy, and the growth mode of the InAlGaN quaternary shows a 2D island growth mode. The minimum surface roughness is 0.20 nm with the TEGa flows equaling to 3.6 \mumol/min in rms. Hall effect measurement results show that the highest electron mobility \mu is 1005.49 cm^2/Vs and the maximal two-dimensional electron gas is 1.63\times10^13 cm^-2.