Epitaxial growth and demonstration of hexagonal BN/AlGaN p-n junctions for deep ultraviolet photonics

Abstract

Recent advances in epitaxial growth and demonstration of p-type conductivity in hexagonal boron nitride (hBN) epilayers represent an exceptional opportunity to revolutionize p-layer approach and overcome the intrinsic problem of low p-type conductivity in Al-rich AlGaN for deep ultraviolet (DUV) device applications. Nevertheless, the ability of epitaxial growth of hBN on AlGaN is a prerequisite for the incorporation of p-type hBN in AlGaN DUV device structures. We report on the epi-growth of hBN on Al-rich AlGaN/AlN/Al2O3 templates using metal organic chemical vapor deposition. X-ray diffraction measurement revealed a 2θ peak at 26.5° which indicates that the BN epilayers are hexagonal and consist of a single phase. Mg doped hBN epilayers were also grown on highly insulating AlN and n-type AlGaN templates with an attempt to demonstrate hBN/AlGaN p-n junctions. Mg doped hBN epilayers grown on insulating templates were p-type with an in-plane resistivity of ∼2.3 Ω cm. Diode behavior in the p-n structures of p-hBN/n-AlxGa1−xN (x ∼ 0.62) has been demonstrated. The results here reveal the feasibility of using highly conductive p-type hBN as an electron blocking and p-contact layers for AlGaN deep UV emitters.