MOCVD optimization and characterization of AlN for the development of an AlN/SiC [p/pn] heterojunction UV detector
Abstract
Nitride based technology has become the popular system for the development of opto-electronic, and electronic devices, such as light emitting diodes (LED's), lasers, high temperature/high power devices, and ultraviolet (UV) emitters and detectors. As a member of the nitride system, aluminum nitride (AlN) is one of the most promising III/V binary materials in these acoustical, opto-electronic, and microwave applications. In binary form and alloyed with gallium nitride (GaN) and indium nitride (InN), AlN has the unique capability of serving as an active, buffer or window layer in short wavelength optoelectronic devices. In order to realize the full potential of AlN and Al based nitrides, it is essential to understand the epitaxial growth of high quality AlN, its doping capability, and device implications. Doping issues in the nitride alloys, e.g. AlxGa1-x N and others, have important implications in fabricating wide-band gap devices, such as ultraviolet detectors and high- temperature, high power transistors. Of particular interest to this research is p-type doping of AlN, and its application in a solid state ultraviolet detector that is not sensitive to visible or IR radiation. In this dissertation, three areas of AlN technology are investigated. First, material characterization is used to compare AlN films grown using various growth conditions and parameters. This will provide a clear understanding of the chemistry and materials science of metal organic chemical vapor deposition (MOCVD) growth of high quality AlN thin films on sapphire, 6H-SiC, and 4H-SiC substrates. Secondly, this research will study the effects of carbon doping levels used to obtain high quality p-type AlN thin films. Finally, this research will demonstrate the AlN technology in an ultraviolet (UV) photodetector device using a window layer of p-AlN on a 4H-SiC pn junction, and the spectral photoresponsivity of this structure will be investigated. Superior properties for AlN in photodiodes can broaden the application for AlGaN, AlInN, and other alloy combinations used to optimize the optical signal wavelengths in the ultraviolet (.2 μm-.4 μm) and visible regions. Practical applications include detection of UV emissions in hot backgrounds for fire control, engine monitoring, imaging for military counter measures, space applications, civilian surveillance, and medical imaging.
- Publication:
-
Ph.D. Thesis
- Pub Date:
- 1999
- Bibcode:
- 1999PhDT.......104W
- Keywords:
-
- Engineering: Materials Science, Engineering: Electronics and Electrical, Physics: Optics