4. Conclusion
In summary, the growth of AlN/GaN/AlN heterostruc-
tures on silicon substrate has been successfully performed
using plasma-assisted MBE. The microstructures and opti-
cal properties of the sample have been revealed by using
HR-XRD, photoluminescence, Raman, TEM, SAED, DF STEM
and HAADF STEM. XRD spectrum confirmed that the
sample was hexagonal structure. Raman spectrum showed
all four Raman-active modes inside the sample. The MSM
UV photodetector fabricated on AlN/GaN/AlN heterostruc-
tures has also been presented. A good photoresponse
result indicates that the device can detect UV light to
produce photo-current response.