Fabrication of InAlGaN/GaN High Electron Mobility Transistors on Sapphire Substrates by Pulsed Metal Organic Chemical Vapor Deposition

Nearly lattice-matched InAIGaN/GaN heterostructure is grown on sapphire substrates by pulsed metal organic chemical vapor deposition and excellent high electron mobility transistors are fabricated on this heterostructure. The electron mobility is 1668.08cm2/V.s together with a high two-dimensional-electron-gas density of 1.43 × 10^13 cm-2 for the InAlCaN/CaN heterostructure of 2Onto InAlCaN quaternary barrier. High electron mobility transistors with gate dimensions of 1 × 50 μm2 and 4μm source-drain distance exhibit the maximum drain current of 763.91 mA/mm, the maximum extrinsic transconductance of 163.13 mS/mm, and current gain and maximum oscillation cutoff frequencies of 11 GHz and 21 GHz, respectively.

Growth and characterization of AlN epilayers using pulsed metal organic chemical vapor deposition

We report the growth of Al N epilayers on c-plane sapphire substrates by pulsed metal organic chemical vapor deposition（MOCVD）. The sources of trimethylaluminium（TMAl） and ammonia were pulse introduced into the reactor to avoid the occurrence of the parasitic reaction. Through adjusting the duty cycle ratio of TMAl to ammonia from 0.8 to 3.0, the growth rate of Al N epilayers could be controlled in the range of 0.24 m/h to 0.93 m/h. The high-resolution x-ray diffraction（HRXRD） measurement showed that the full width at half maximum（FWHM） of the（0002） and（10-12） reflections for a sample would be 194 arcsec and 421 arcsec, respectively. The step-flow growth mode was observed in the sample with the atomic level flat surface steps, in which a root-mean-square（RMS） roughness was lower to 0.2 nm as tested by atomic force microscope（AFM）. The growth process of Al N epilayers was discussed in terms of crystalline quality, surface morphology,and residual stress.

Superior material qualities and transport properties of InGaN channel heterostructure grown by pulsed metal organic chemical vapor deposition

Pulsed metal organic chemical vapor deposition is introduced into the growth of InGaN channel heterostructure for improving material qualities and transport properties. High-resolution transmission electron microscopy imaging shows the phase separation free InGaN channel with smooth and abrupt interface. A very high two-dimensional electron gas density of approximately 1.85 x 10^13 cm-2 is obtained due to the superior carrier confinement. In addition, the Hall mobility reaches 967 cruZ/V-s, owing to the suppression of interface roughness scattering. Furthermore, temperature-dependent Hall measurement results show that InGaN channel heterostructure possesses a steady two-dimensional electron gas density over the tested temperature range, and has superior transport properties at elevated temperatures compared with the traditional GaN channel heterostructure. The gratifying results imply that InGaN channel heterostructure grown by pulsed metal organic chemical vapor deposition is a promising candidate for microwave power devices.