Reduction of reverse‐leakage current in selective‐area‐grown GaN‐based core–shell nanostructure LEDs using AlGaN layers

We report a simple method to improve the p‐type doping efficiency and eliminate the diode leakage current in selective‐area‐grown GaN‐based core–shell nanostructure LEDs by growing an n‐type AlGaN layer underneath the InGaN/GaN active region. A significant reduction in reverse‐leakage current density is correlated with longer AlGaN layer growth time and higher flow rate of the aluminum precursor. A comparison of the SIMS profiles with and without the underlayer indicates a high concentration of donor‐type impurities (e.g., silicon and oxygen) in the p‐GaN layer in the structure with no AlGaN underlayer. Conversely, LEDs with an AlGaN underlayer exhibit enhanced magnesium incorporation and much lower silicon and oxygen impurity concentrations within the p‐GaN layer. The reverse current density was also reduced by the addition of a p‐type AlGaN electron blocking layer above the active region.