  N-type doping of high-resistance wide bandgap semiconductors, wurtzite
high-Mg-content MgxZn1-xO for instance, has always been a fundamental
application-motivated research issue. Herein, we report a solution to enhancing
the conductivity of high-resistance Mg0.51Zn0.49O active components, which has
been reliably achieved by fluorine doping via radio-frequency plasma assisted
molecular beam epitaxial growth. Fluorine dopants were demonstrated to be
effective donors in Mg0.51Zn0.49O single crystal film having a solar-blind 4.43
eV bandgap, with an average concentration of 1.0E19 F/cm3.The dramatically
increased carrier concentration (2.85E17 cm-3 vs ~1014 cm-3) and decreased
resistivity (129 ohm.cm vs ~10E6 ohm cm) indicate that the electrical
properties of semi-insulating Mg0.51Zn0.49O film can be delicately regulated by
F doping. Interestingly, two donor levels (17 meV and 74 meV) associated with F
were revealed by temperature-dependent Hall measurements. A Schottky type
metal-semiconductor-metal ultraviolet photodetector manifests a remarkably
enhanced photocurrent, two orders of magnitude higher than that of the undoped
counterpart. The responsivity is greatly enhanced from 0.34 mA/W to 52 mA/W
under 10 V bias. The detectivity increases from 1.89E9 cm Hz1/2/W to 3.58eE10
cm Hz1/2/W under 10 V bias at room temperature.These results exhibit F doping
serves as a promising pathway for improving the performance of high-Mg-content
MgxZn1-xO-based devices.
