AlGaN photodetectors grown on Si(111) by molecular beam epitaxy

The fabrication and characterisation of AlxGa1-xN (0 less than or equal to x less than or equal to 0.35) photodetectors grown on Si(1 1 1) by molecula r beam epitaxy are described. For low Al contents (< 10%), photoconductors show high responsivities ( similar to 10A/W), a non-linear dependence on op tical power and persistent photoconductivity (PPC). For higher Al contents the PPC decreases and the photocurrent becomes linear with optical power. S chottky photodiodes present zero-bias responsivities from 12 to 5 mA/W (x=0 -0.35), a UV/visible contrast higher than 10(3), and a time response of sim ilar to 20 ns, in the same order of magnitude as for devices on sapphire su bstrate. GaN-based p-n ultraviolet photodiodes on Si(1 1 1) are reported fo r the first time. (C) 2001 Elsevier Science B.V. All rights reserved.