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 to3.6μmol/min in rms.Hall effect measurement results show that the highest electron mobility μ is 1005.49cm~2/Vs and the maximal two-dimensional electron gas is 1.63×10~(13) cm~(-2). 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 μmol / min in rms. Hall effect measurement results show that the highest electron mobility μ is 1005.49 cm ~ 2 / Vs and the maximal two-dimensional electron gas is 1.63 × 10 ~ (13) cm ~ (-2).