Characterization of GaN/AlGaN epitaxial layers grown by metalorganic chemical vapour deposition for high electron mobility transistor applications

GaN and AlGaN epitaxial layers are grown by a metalorganic chemical vapour deposition (MOCVD) system. The crystalline quality of these epitaxially grown layers is studied by different characterization techniques. PL measurements indicate band edge emission peak at 363.8 nm and 312 nm for GaN and AlGaN layers respectively. High resolution XRD (HRXRD) peaks show FWHM of 272 and 296 arcsec for the (0 0 0 2) plane of GaN and GaN in GaN/AlGaN respectively. For GaN buffer layer, the Hall mobility is 346 cm2/V-s and carrier concentration is 4.5 × 1016/cm3. AFM studies on GaN buffer layer show a dislocation density of 2 × 108/cm2 by wet etching in hot phosphoric acid. The refractive indices of GaN buffer layer on sapphire at 633 nm are 2.3544 and 2.1515 for TE and TM modes respectively.

[1]  U. K. Mishra,et al.  Metalorganic chemical vapor deposition growth of high optical quality and high mobility GaN , 1995 .

[2]  T. Kozawa,et al.  Dislocation etch pits in GaN epitaxial layers grown on sapphire substrates , 1996 .

[3]  G. G. Stokes.  "J." , 1890, The New Yale Book of Quotations.

[4]  U. Mishra,et al.  30-W/mm GaN HEMTs by field plate optimization , 2004, IEEE Electron Device Letters.

[5]  Andrew G. Glen,et al.  APPL , 2001 .

[6]  Ho-Young Cha,et al.  The Effect of an Fe-doped GaN Buffer on off-State Breakdown Characteristics in AlGaN/GaN HEMTs on Si Substrate , 2006, IEEE Transactions on Electron Devices.

[7]  J. Guo,et al.  The dependence of the electrical characteristics of the GaN epitaxial layer on the thermal treatment of the GaN buffer layer , 1996 .

[8]  P. Vennégués,et al.  Growth of high-quality GaN by low-pressure metal-organic vapour phase epitaxy (LP-MOVPE from 3D islands and lateral overgrowth , 1999 .

[9]  L. Eastman,et al.  Comparison of GaN HEMTs on Diamond and SiC Substrates , 2007, IEEE Electron Device Letters.

[10]  Marc Ilegems,et al.  Infrared Lattice Vibrations and Free-Electron Dispersion in GaN , 1973 .

[11]  Z. J. Yang,et al.  Reduction of threading edge dislocation density in n-type GaN by Si delta-doping , 2006 .

[12]  Isamu Akasaki,et al.  Effects of ain buffer layer on crystallographic structure and on electrical and optical properties of GaN and Ga1−xAlxN (0 < x ≦ 0.4) films grown on sapphire substrate by MOVPE , 1989 .

[13]  Surjya K. Pal,et al.  Silicon—a new substrate for GaN growth , 2004 .