Ultraviolet photodetectors based on GaN and AlxGa1-xN epitaxial layers

The effect of epilayer structural peculiarities on electro- physical properties of the epilayers and on parameters of the UV photodetectors has been investigated. Random distribution of charged centers, which is associated with boundaries of mosaic structure domains being typical of III- nitrides, has been shown to result in a low Schottky barrier height, a high leakage current, and persistent photoconductivity in an undoped GaN. The introduction of low Si concentration minimized the effect as well as allows the Schottky barrier height to be obtained close to the difference between work functions of GaN and metal. The characteristics of Al 0,1 Ga 0.9 N Schottky barrier photodetectors have been given. MSM photodetectors and Schottky barrier photodetectors over spectral range 200-365 nm with characteristics close to those of the best analogs, in particular, leakage current density of about 10 -8 A cm -2 , have been obtained using domestic GaN grown by MOCVD on sapphire substrates of (0001) orientation.