A. Yamamoto

Effect of gas flow on the growth of In-rich AlInN films by metal-organic chemical vapor deposition

Indium-rich AlInN are grown by metal-organic (MO) chemical vapor deposition using trimethylaluminum, trimethylindium, and ammonia. Under the conservation of MO influx, the effects of gas flow in the MO route on AlInN growth and Al-related parasitic reaction are investigated. With an increase in this gas flow, the suppression of Al-related parasitic reaction, i.e., enhancement in Al content incorporation and improvement of crystalline quality, is satisfactorily shown until the occurring of severe phase separation. Accordingly, Al content x in Al x In 1 − x N can be tuned from x = 0.02 to 0.26. The Raman spectra of those AlInN samples with phase separation are analyzed by the resonant excitation effect and two-mode behavior for A 1 ( LO ) . Finally, we propose a phase diagram to interpret the phase separation and Al content evolution under the influence of gas flow.

Terahertz characterization of semiconductor alloy AlInN: negative imaginary conductivity and its meaning

Through terahertz time-domain spectroscopy, negative imaginary conductivity is observed in In-rich AlInN film grown by metal-organic chemical-vapor deposition for frequencies from 0.2 to 2.0 THz. This non-Drude behavior is explained based on the electron back-scattering theory of Smith [Phys. Rev. B65, 115206 (2002)]. Comparing with binary semiconductor InN, potential fluctuations produced by composition inhomogeneity and alloy scattering of carriers make In-rich AlInN alloy easier to be subjected to non-Drude behavior in electrical performance.

Misfit Dislocation Reduction of InxGa1-xN/GaN Heteroepitaxy Using Graded Layer

The performances of heterostructural devices are often limited by misfit dislocation. In this paper, a theoretical approach for misfit dislocation reduction of wurtzite InxGa1-xN/GaN is presented. The linear and exponential grading techniques have been modeled for the reduction of dislocation. An energy balance model has been taken into consideration and modified for wurtzite structure to evaluate the misfit dislocation density. The value of misfit dislocation has been reduced from 7.112×1010 cm-2 to 6.19×106 cm-2 and 7.039×1010 cm-2 to 6.121×106 cm-2 at the plane 1/3<> {} and 1/3<>{} respectively for linear grading. In case of exponential grading the dislocation density has been reduced to 2.762×105 cm-2 for both slip systems. Because of tapered grading coefficient a tapered dislocation profile has been reported in case of exponential grading technique. Finally, a comparative study has been shown among without graded, linear and exponential grading.