Revealing the surface electronic structures of AIGaN deep-ultraviolet multiple quantum wells with lateral polarity domains

We report on the carrier dynamic and electronic structure investigations on AlGaN-based deep-ultraviolet multiple quantum wells (MQWs)with lateral polarity domains.The localized potential maximum is predicted near the domain boundaries by first-principle calculation,suggesting carrier localization and efficient radiative recombination.More importantly,lateral band diagrams of the MQWs are proposed based on electron affinities and valance band levels calculated from ultraviolet(UV)photoelectron spectroscopy.The proposed lateral band diagram is further demonstrated by surface potential distribution collected by Kelvin probe microscopy and the density-of-state calculation of energy bands.This work illustrates that lateral polarity structures are playing essential roles in the electronic properties of II nitride photonic devices and may provide novel perspective in the realization of high-efficiency UV emitters.

Lateral polarity control ofⅢ-nitride thin film and application in GaN Schottky barrier diode

N-polar and Ⅲ-polar GaN and AlN epitaxial thin films grown side by side on single sapphire substrate was reported.Surface morphology,wet etching susceptibility and bi-axial strain conditions were investigated and the polarity control scheme was utilized in the fabrication of Schottky barrier diode where ohmic contact and Schottky contact were deposited on N-polar domains and Ga-polar domains,respectively.The influence of N-polarity on on-state resistivity and Ⅰ–Ⅴ characteristic was discussed,demonstrating that lateral polarity structure of GaN and AlN can be widely used in new designs of optoelectronic and electronic devices.