Si Donor Incorporation in GaN Nanowires

With increasing interest in GaN based devices, the control and evaluation of doping are becoming more and more important. We have studied the structural and electrical properties of a series of Si-doped GaN nanowires (NWs) grown by molecular beam epitaxy (MBE) with a typical dimension of 2–3 μm in length and 20–200 nm in radius. In particular, high resolution energy dispersive X-ray spectroscopy (EDX) has illustrated a higher Si incorporation in NWs than that in two-dimensional (2D) layers and Si segregation at the edge of the NW with the highest doping. Moreover, direct transport measurements on single NWs have shown a controlled doping with resistivity from 10² to 10^–3 Ω·cm, and a carrier concentration from 10¹⁷ to 10²⁰ cm^–3. Field effect transistor (FET) measurements combined with finite element simulation by NextNano³ software have put in evidence the high mobility of carriers in the nonintentionally doped (NID) NWs.