Sub-nanometer ultrathin epitaxy of AlGaN and its application in efficient doping

Solving the doping asymmetry issue in wide-gap semiconductors is a key difficulty and long-standing challenge for device applications.Here,a desorption-tailoring strategy is proposed to juggle the carrier concentration and transport.Specific to the p-doping issue in Al-rich AlGaN,self-assembled p-AlGaN superlattices with an average Al composition of over 50％are prepared by adopting this approach.The hole concentration as high as 8.1×1018cm-3 is thus realized at room temperature,which is attributed to the significant reduction of effective Mg activation energy to 17.5 meV through modulating the activating path,as well as the highlighted Mg surface-incorporation by an intentional interruption for desorption.More importantly,benefiting from the constant ultrathin barrier thickness of only three monolayers via this approach,vertical miniband transport of holes is verified in the p-AlGaN superlattices,greatly satisfying the demand of hole injection in device application.280 nm deep-ultraviolet light-emitting diodes are then fabricated as a demo with the desorption-tailored Al-rich p-AlGaN superlattices,which exhibit a great improvement of the carrier injection efficiency and light extraction efficiency,thus leading to a 55.7％increase of the light output power.This study provides a solution for p-type doping of Al-rich AlGaN,and also sheds light on solving the doping asymmetry issue in general for wide-gap semiconductors.