Polarity dependence of AlN {0001} decomposition in flowing H2

Abstract The thermal stabilities of Al- and N-polarity AlN layers grown on (0 0 0 1) sapphire substrates were investigated at temperatures ranging from 1100 to 1400 °C in various gas flows (He, H 2 and H 2 +NH 3 ). Decomposition of AlN occurred in flowing H 2 , while it did not occur in He or H 2 +NH 3 flow. The decomposition rate in H 2 increased with an increase in the temperature over 1200 °C, and the decomposition rate of the Al-polarity AlN layer was found to be lower than that of the N-polarity AlN layer at each temperature. The decomposition reaction of AlN and the relationship between the polarities of the AlN layers and their different decomposition rates are discussed.

[1]  L. Walker,et al.  Wet Chemical Etching of AlN Single Crystals , 2002 .

[2]  Martin Kuball,et al.  Bulk AlN crystal growth: self-seeding and seeding on 6H-SiC substrates , 2002 .

[3]  Y. Ohba,et al.  Growth of AlN on sapphire substrates by using a thin AlN buffer layer grown two-dimensionally at a very low V/III ratio , 2000 .

[4]  K. Hiramatsu,et al.  Growth of Thick AlN Layer by Hydride Vapor Phase Epitaxy , 2005 .

[5]  J. Jasinski,et al.  Inversion domains in AlN grown on (0001) sapphire , 2003 .

[6]  A. Winnacker,et al.  Structural properties of AlN crystals grown by physical vapor transport , 2005 .

[7]  Y. Kumagai,et al.  Influence of lattice polarity on wurzite GaN{0 0 0 1} decomposition as studied by in situ gravimetric monitoring method , 2002 .

[8]  A. Usikov,et al.  Thick AlN layers grown by HVPE , 2005 .

[9]  I. Ivanov,et al.  High-Quality 2'' Bulk-Like Free-Standing GaN Grown by HydrideVapour Phase Epitaxy on a Si-doped Metal Organic Vapour Phase Epitaxial GaN Template with an Ultra Low Dislocation Density , 2005 .

[10]  Y. Xi,et al.  Very high quality AlN grown on (0001) sapphire by metal-organic vapor phase epitaxy , 2006 .

[11]  N. Newman,et al.  Experimental determination of the rates of decomposition and cation desorption from AlN surfaces , 2001 .

[12]  S. Kamiyama,et al.  Microstructure of thick AlN grown on sapphire by high‐temperature MOVPE , 2006 .

[13]  Yiying Wu,et al.  Effect of nitridation on polarity, microstructure, and morphology of AlN films , 2004 .

[14]  Toru Nagashima,et al.  High-speed epitaxial growth of AlN above 1200∘C by hydride vapor phase epitaxy , 2007 .

[15]  Yoshinao Kumagai,et al.  Preparation of Large Freestanding GaN Substrates by Hydride Vapor Phase Epitaxy Using GaAs as a Starting Substrate : Semiconductors , 2001 .

[16]  T. Ichihashi,et al.  Preparation of Freestanding GaN Wafers by Hydride Vapor Phase Epitaxy with Void-Assisted Separation , 2003 .

[17]  Oliver Ambacher,et al.  Large Free-Standing GaN Substrates by Hydride Vapor Phase Epitaxy and Laser-Induced Liftoff , 1999 .

[18]  A. Kelly,et al.  The estimation of dislocation densities in metals from X-ray data , 1953 .

[19]  Y. Kumagai,et al.  Improvement of crystalline quality of N-polar AlN layers on c-plane sapphire by low-pressure flow-modulated MOCVD , 2007 .

[20]  A. Wickenden,et al.  Enhanced GaN decomposition in H2 near atmospheric pressures , 1998 .

[21]  Y. Kumagai,et al.  Growth of thick AlN layers by hydride vapor-phase epitaxy , 2005 .

[22]  Y. Makarov,et al.  Sublimation growth of AlN bulk crystals in Ta crucibles , 2005 .

[23]  K. E. Morgan,et al.  Report on the growth of bulk aluminum nitride and subsequent substrate preparation , 2001 .

[24]  M. Boćkowski,et al.  Crystal growth of aluminum nitride under high pressure of nitrogen , 2001 .

[25]  Y. Mori,et al.  Synthesis of AlN Grains and Liquid-Phase-Epitaxy (LPE) Growth of AlN Films Using Sn-Ca Mixed Flux , 2005 .

[26]  Rafael Dalmau,et al.  Seeded growth of AlN bulk single crystals by sublimation , 2002 .

[27]  S. Park,et al.  Free-Standing GaN Substrates by Hydride Vapor Phase Epitaxy , 2000 .

[28]  K. Kamei,et al.  LPE growth of AlN from Cu–Al–Ti solution under nitrogen atmosphere , 2006 .

[29]  K. Hiramatsu,et al.  High‐quality AlN epitaxial films on (0001)‐faced sapphire and 6H‐SiC substrate , 2003 .