Molecular Beam Epitaxy of AlGaN Epilayers on Si for Vertical Deep Ultraviolet Light-Emitting Diodes

Abstract

Silicon (Si) has been an appealing substrate for vertical aluminum gallium nitride (AlGaN) deep ultraviolet (UV) light-emitting diodes (LEDs), toward which, the first step is to demonstrate AlGaN deep UV LEDs on Si. Nonetheless, the epitaxy of AlGaN epilayers on Si remains a challenge. Herein, we demonstrate the molecular beam epitaxy of AlGaN epilayers on Si using a nanowire-based template over a wide Al content range from 35%–70%. Smooth AlGaN surface down to a rms roughness of 0.4 nm is obtained using this approach. Vertical AlGaN deep UV LEDs emitting down to 247 nm are also demonstrated.