MOCVD growth and characterization of ultrathin AlN/GaN superlattices on 0001 sapphire substrates

Marek Wojcik ,  Jarosław A. Gaca ,  Andrzej Turos ,  Wlodek Strupinski 

Institute of Electronic Materials Technology (ITME), Wólczyńska 133, Warszawa 01-919, Poland


AlN/GaN superlattices (SLs) have been subject of intense investigation due to their potential applications for high power transistors and ultraviolet laser diodes. However, only a few reports are focused to their structural properties. In this work we report on the extended study of strained AlN/GaN SLs. Utrathin (0.42/0.48 nm) AlN/GaN SLs were grown by the MOCVD technique on the top of a structure composed of thick 1000 nm AlxGa(1-x)N buffer layer, and AlN nucleation layer (≈20nm) on the vicinal sapphire (0001) substrates. These samples were analyzed by means of high resolution x-ray diffraction (HRXRD) techniques, and cross-sectional transmission electron microscopy (TEM). It was found that for AlxGa(1-x)N layers with the same Al content as the average Al content in the whole volume of AlN/GaN SLs exhibit a good in-wafer composition uniformity. .Moreover, no relaxation was observed i.e. both AlN and GaN layers have the same in-plane lattice parameter as the underlying buffer layer. The buffer layer is hence an effective substrate for the two-dimensional growth and ensures the proper the chemical and crystalline order of the AlN/GaN SLs. The strain evolution in the SLs structures is assessed by the high-resolution x-ray diffraction and reciprocal space mapping (RSM), using numerical simulation methods. It has also been shown that x-ray methods are sensitive enough to provide data necessary to determine chemical composition profile and crystallographic order even in the case of extremely thin AlN and GaN layers.


Related papers
  1. The influence of pressure on growth of 3C-SiC heteroepitaxial layers on silicon substrates
  2. CVD of graphene on SiC
  3. Pinned and unpinned epitaxial and sublimated graphene on SiC
  4. Topographic and reflectometric investigation of 4H silicon carbide epitaxial layer deposited at various growth rates
  5. Synthesis of gallium nitride nanowires by Sublimation Sandwich Method
  6. Raman spectroscopy of single and multilayer graphene on SiC substrates
  7. Growth of GaN layers on silicon and sintered GaN nano-ceramic substrates – TEM investigations
  8. Growth of high resistivity GaN layers by compensating defects generation
  9. Effects of composition grading at the heterointefaces and Layers Thickness Variations on Bragg Mirror Quality
  10. Electrical Properties of GaN/AlGaN Hetrostructures
  11. GaN growth by Sublimation Sandwich Method
  12. Mg diffusion in GaN:Mg grown by metalorganic vapor-phase epitaxy MOVPE
  13. Optical investigations of two dimensional electron gas in the AlGaN/GaN heterostructures
  14. Problems with cracking of AlxGa1-xN layers

Presentation: Poster at Joint Fith International Conference on Solid State Crystals & Eighth Polish Conference on Crystal Growth, by Marek Wojcik
See On-line Journal of Joint Fith International Conference on Solid State Crystals & Eighth Polish Conference on Crystal Growth

Submitted: 2007-01-11 13:40
Revised:   2009-06-07 00:44