Preparation of degenerate n-type AlxGa1−xN (0 < x ≤ 0.81) with record low resistivity by pulsed sputtering deposition

Abstract

Highly conductive AlGaN alloys hold a great technological potential, wherein the degenerate n-type doping is key in reducing parasitic resistances in electronic and opto-electronic devices. Nonetheless, AlxGa1−xN elaborated in conventional methods exhibits degraded electron concentration at high Al compositions. Here, we demonstrated the growth of degenerate n-type AlxGa1−xN (0 < x ≤ 0.81) with record high electron concentrations by using the pulsed sputtering deposition (PSD) method. The fabricated samples were investigated by cathodoluminescence and Hall-effect measurements in studying the related deep-level emission and electron mobility, respectively. Our findings showed that the PSD-grown heavily Si-doped AlxGa1−xN exhibits record low resistivity values: 2.5 × 10−3 Ω cm with an electron concentration of 1.2 × 1020 cm−3 for x = 0.60 and 1.7 × 10−2 Ω cm with an electron concentration of 3.2 × 1019 cm−3 for x = 0.81. Temperature-dependent Hall-effect measurements confirmed the degenerate nature of heavily Si-doped AlxGa1−xN up to x = 0.81. These results clearly show that the PSD n-type AlGaN is quite promising for reducing parasitic resistance in AlGaN based far UVC light-emitting devices and high breakdown voltage electron devices.