Coaxial InGaN epitaxy around GaN micro-tubes: Tracing the signs

This work focuses on investigations of the luminescence properties of coaxial InGaN layers grown around single GaN micro and sub-micron tubes on top of GaN micro-pyramids. The tube structure was formed after the controlled desorption of ZnO nano-pillar templates during the coaxial GaN epitaxy. A thin layer near the area around the inner diameter of the micro-tube is believed to be heavily doped with Zn impurities leading to an intense and broad photoluminescence (PL) peak centered around 2.85 eV that quenches the luminescence from coaxial InGaN quantum wells (QWs). When the thickness of the GaN tube wall before the QW growth was doubled, a clear indication of In incorporation in low temperature PL was observed via an intense peak around 3.1 eV. Moreover, as the temperature of the QW growth was changed from 830 °C to 780 °C, a shift of the peak corresponding to an increase in In incorporation from 3.5% to 7.5% was noticed.

► MOCVD challenges for obtaining luminescent coaxial InGaN QWs around GaN micro-tubes.
► Evidence of In incorporation into coaxial InGaN layers around GaN micro-tubes.
► Characterization: photoluminescence and spatially resolved cathodoluminescence.