Nitride Nanocolumns for the Development of Light-Emitting Diode

The progress of light-emitting-diode (LED) development based on nitride nanocolumn (NC) growth, including InGaN/GaN quantum-well (QW) growth on NCs and regularly arranged GaN NC growth, is first reviewed. Then, the coalescence-overgrowth results based on patterned GaN NC growth are introduced. The overgrowth quality dependence on NC cross-sectional size and NC spacing size is discussed. Generally, a smaller NC dimension and spacing size lead to higher overgrowth quality, including lower threading dislocation (TD) density and larger lateral domain size. Next, the emission enhancement results of blue- and green-emitting InGaN/GaN QW and LED structures based on NC growth and coalescence overgrowth are presented. Significant enhancements (up to ~100% output intensity increase in a blue LED) are demonstrated. For LED applications, the TD density reduction in an overgrown GaN template can more effectively enhance the emission efficiency of a blue LED, when compared with a green LED.