Proceedings Article | 13 October 2009
Proc. SPIE. 7518, Photonics and Optoelectronics Meetings (POEM) 2009: Solar Cells, Solid State Lighting, and Information Display Technologies
KEYWORDS: Diffraction, Visible radiation, Ultraviolet radiation, Crystals, Interfaces, Sapphire, Transmittance, Aluminum, Metalorganic chemical vapor deposition, Ultraviolet detectors
The epitaxial layer quality of Al<sub>x</sub>Ga<sub>1-x</sub>N (x>0.6) on sapphire substrate grown by metal organic chemical vapor
deposition (MOCVD) needs to be further improved. In this paper, we evaluated the properties of defects, lattice
mismatch between epitaxial layer and substrate, crystal quality and conductivity for these high Al mole fraction
materials from the viewpoint of fabricating high performance solar blind detectors by comprehensive utilizing
various undamaged measurements. The measurement of transmission spectrum was used to evaluate the absorption
edge, band gap, mole fraction of Al content, hetero-epitaxial interface, and transmissivity in the ultraviolet spectral
range. X-ray diffraction (XRD) was used to measure the component of the AlGaN material, uniformity of the
material and crystal quality. The conductivity of the surface layer of the AlGaN film material was obtained by using
high precision current-voltage curve measurement. In short, the material quality, optical and electrical properties,
and uniformity for high Al mole fraction AlGaN epitaxial layers were qualitatively or quantitatively measured and
analyzed. These works lay the foundation for manufacturing high performance solar blind ultraviolet detectors
based on high Al mole fraction AlGaN epitaxial materials on sapphire substrate.
