|
Gallium nitride features some unique
properties such as large band gap, strong interatomic bonds, and high thermal
conductivity.
Applications
Along the last decade, GaN has attracted
great interests owing to its potential applications in high power and high
frequency electronic devices as well as in blue LED devices. GaN layers are
usually grown by Metal Organic Chemical Vapor Deposition and the Molecular Beam
Epitaxy methods.
Figure 1. GaN, different sample preparation conditions. Image size 5x5 um,
Z-range 1.5 nm
Sapphire
Substrate
Sapphire is now the most commonly used
substrate although of its highly mismatched lattice and thermal expansion
coefficients. As a consequence, the obtained GaN layers often contain a large
number defects, mainly dislocations.
Steps and Screw
Dislocations
The image shows a piece of GaN with steps
and screw dislocations (holes). The goal is to count number of dislocations and
step distribution. |