7 April 1999 Electrical characterization of AlxGa1-xN for UV photodetector applications
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Abstract
Ultraviolet photodetectors have many military and commercial applications. However, for many of these applications, the photodetectors must be solar blind. This means that the photodetectors must have a cutoff wavelength of less than about 270 nm. Semiconductor based devices would then need energy gaps of over 4.6 eV. In the AlxGa1-xN system, the aluminum mole fraction, x, required is over 40%. As the energy gap is increased, doping becomes much more difficult, especially p-type doping. This report is a study of the electrical properties of AlxGa1-xN to enable better control of the doping. Magnesium doped p-type AlxGa1- xN has been studied using high-temperature Hall effect measurements. The acceptor ionization energy has been found to increase substantially with the aluminum content. Short-period superlattices consisting of alternating layers of GaN:Mg and AlGaN:Mg were also grown by low-pressure organometallic vapor phase epitaxy. The electrical properties of these superlattices were measured as a function of temperature and compared to conventional AlGaN:Mg layers. It is shown that the optical absorption edge can be shifted to shorter wavelengths while lowering the acceptor ionization energy by using short- period superlattice structures instead of bulk-like AlGaN:Mg. Silicon doped n-type films have also been studied.
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Adam W. Saxler, Adam W. Saxler, Mohamad Ahoujja, Mohamad Ahoujja, W. C. Mitchel, W. C. Mitchel, Patrick Kung, Patrick Kung, Danielle Walker, Danielle Walker, Manijeh Razeghi, Manijeh Razeghi, } "Electrical characterization of AlxGa1-xN for UV photodetector applications", Proc. SPIE 3629, Photodetectors: Materials and Devices IV, (7 April 1999); doi: 10.1117/12.344558; https://doi.org/10.1117/12.344558
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