Tunable p-type conductivity and transport properties of AlN nanowires via Mg doping

Arrays of well-aligned AlN nanowires (NWs) with tunable p-type conductivity were synthesized on Si(111) substrates using bis(cyclopentadienyl)magnesium (Cp₂Mg) vapor as a doping source by chemical vapor deposition. The Mg-doped AlN NWs are single-crystalline and grow along the [001] direction. Gate-voltage-dependent transport measurements on field-effect transistors constructed from individual NWs revealed the transition from n-type conductivity in the undoped AlN NWs to p-type conductivity in the Mg-doped NWs. By adjusting the doping gas flow rate (0-10 sccm), the conductivity of AlN NWs can be tuned over 7 orders of magnitude from (3. 8-8. 5) × 10^-6Ω ^-1 cm^-1 for the undoped sample to 15. 6-24. 4Ω ^-1 cm^-1 for the Mg-doped AlN NWs. Hole concentration as high as 4. 7 × 10¹⁹ cm^-3 was achieved for the heaviest doping. In addition, the maximum hole mobility (∼ 6. 4 cm ²/V s) in p-type AlN NWs is much higher than that of Mg-doped AlN films (∼ 1. 0 cm²/V s). ² The realization of p-type AlN NWs with tunable electrical transport properties may open great potential in developing practical nanodevices such as deep-UV light-emitting diodes and photodetectors. © 2011 American Chemical Society.