"Classic" and Novel Methods of Dislocation Reduction in Heteroepitaxial Nitride Layers

Jacek Jasiński 

Lawrence Berkeley National Laboratory, National Center for Electron Microscopy (LBNL), Berkeley, CA, United States

Abstract

One of the main problems of nitride-based technology is the lack of commercially available large native substrates. Commonly used substrates, such as sapphire or 6H-SiC, are poorly matched in terms of lattice parameters and thermal expansion coefficients. This leads to high densities of threading dislocations (typically in the range of 1010-1011 cm-2), which seriously limits the performance of nitride-based devices. Dislocations are believed to reduce the mobility and lifetime of electrical carriers, provide paths for diffusion of impurities and serve as leakage current pathways. They also seem to be responsible for the degradation of nitride laser structures. To address these problems several different methods of dislocation density reduction have been proposed in recent years. Early methods utilized growth of buffer layers and were aimed at controlling the number of nucleation sites and lowering the strain at the interface area. They brought down the dislocation density to the range of 108-109 cm-2. However, further reduction was possible due to the development of other methods. First group of such methods, known as epitaxial lateral overgrowth methods, are designed to change the dislocation propagation from vertical to horizontal redirecting them from the active layer of the nitride structure. In other methods an insertion of intermediate layers or growth of thick nitride layers increases the probability of interactions between dislocations resulting in their combination and/or annihilation. There are also methods that attempt to combine these approaches. They include growth on porous substrates or growth interruption combined with in situ surface treatment with anti-surfactants. In this paper all different methods will be reviewed and compared. Their advantages and limitations, as well as, specific mechanisms of dislocation reduction will be discussed.

Legal notice
  • Legal notice:

    Copyright (c) Pielaszek Research, all rights reserved.
    The above materials, including auxiliary resources, are subject to Publisher's copyright and the Author(s) intellectual rights. Without limiting Author(s) rights under respective Copyright Transfer Agreement, no part of the above documents may be reproduced without the express written permission of Pielaszek Research, the Publisher. Express permission from the Author(s) is required to use the above materials for academic purposes, such as lectures or scientific presentations.
    In every case, proper references including Author(s) name(s) and URL of this webpage: http://science24.com/paper/1769 must be provided.

 

Related papers
  1. Characterization of the Surface Chemistry of Iron Oxide Nanoparticles in the Transmission Electron Microscope

Presentation: invited oral at E-MRS Fall Meeting 2004, Symposium C, by Jacek Jasiński
See On-line Journal of E-MRS Fall Meeting 2004

Submitted: 2004-04-27 20:35
Revised:   2009-06-08 12:55
Google
 
Web science24.com
© 1998-2022 pielaszek research, all rights reserved Powered by the Conference Engine