11.5 Post Growth Characterization of Nitride Films - X-Ray Analysis
X-ray Analysis (Ref. 50) was employed to check our GaN films and their
quality. A typical scans for wurtzite GaN grown on c-plane sapphire is
shown in Figure 45, using Cu K_alpha emission. As can be seen in the figure,
GaN grown on c-plane sapphire has the main peak (0002) at 2theta=34.6°,
as well as a smaller peak (0004) at 73.0°. GaN grown on a-plane sapphire
has 2 dominating peaks, the (0002) peak at 34.6° and another (so far
unidentified) peak at 37.8°, as well as a minor (0004) peak. This suggests
(see also section on RHEED) that GaN grown on c-plane sapphire keeps its
orientation, while GaN grown on a-plane sapphire is c-plane oriented as
well. Both X-ray scans compare well with scans in the literature.
X-ray rocking curves were obtained on the 0002 peaks. GaN grown on c-plane
sapphire as well as a-plane revealed a Full Width at Half Maximum (FWHM)
of better than 20', which was also the resolution limit of the machine
used. Therefore those measurements have to be repeated on a high resolution
X-ray machine because the original machine is known to have poor X-ray
optics and lacks the fine adjustments needed to line up the sample properly.
Preparations to do those measurements are currently underway.
Figure 45: X-Ray scan of Wurtzite GaN (Cu K_alpha)
Table of Contents