Growth of Si-doped AlN on sapphire (0001) via pulsed sputtering

Yuya Sakurai,Jitsuo Ohta,Hideto Miyake,Kohei Ueno,Atsushi Kobayashi,Hiroshi Fujioka

doi:10.1063/1.5051555

Abstract

The Si-doped AlN films were grown on sapphire (0001) by pulsed sputtering deposition (PSD), and their structural and electrical properties were investigated. A combination of PSD and high-temperature annealing process enabled the growth of high-quality AlN (0001) epitaxial films on sapphire (0001) substrates with atomically flat stepped and terraced surfaces. The transmission electron microscopy observations revealed that the majority of the threading dislocations in AlN belonged to the mixed- or edge-type, with densities of 2.8 × 108 and 4.4 × 109 cm−2, respectively. The Si-doping of AlN by PSD yielded a clear n-type conductivity with a maximum electron mobility of 44 cm2 V−1 s−1, which was the highest value reported for AlN that was grown on sapphire. These results clearly demonstrated the strong potential of the PSD technique for growing high-quality conductive n-type AlN on sapphire.

Highlights

AlN and its alloy with Ga are promising materials for ultraviolet (UV) light-emitting diodes (LEDs) because of their tunable wide bandgap that ranges from 3.4 to 6.2 eV
The Sidoping of AlN on sapphire via metal-organic chemical vapor deposition (MOCVD) yielded a poor n-type conductivity of 2 mS cm at an electron concentration of 4 × 1015 cm−3.2 This poor n-type conductivity was attributed to the large activation energy of the dopant, the low crystalline quality, and the formation of intrinsic and extrinsic point defects, including the DX-like behavior of Si.[3]
For n-type doping in GaN by pulsed sputtering deposition (PSD), the electron concentration can be controlled between 1 × 1016 and 5 × 1020 cm−3, while maintaining a high electron mobility

Summary

Introduction

AlN and its alloy with Ga are promising materials for ultraviolet (UV) light-emitting diodes (LEDs) because of their tunable wide bandgap that ranges from 3.4 to 6.2 eV. We describe the growth of high-quality AlN epitaxial films on the sapphire (0001) substrates and investigation of the feasibility of Si-doping in AlN on sapphire by PSD.

Results

Conclusion