Transport imaging for contact-free measurements of minority carrier diffusion in GaN, GaN/AlGaN, and GaN/InGaN core-shell nanowires

Minority carrier diffusion lengths (Ld) are measured for GaN, GaN/AlGaN, and GaN/InGaN core-shell nanowires using a technique based on imaging of recombination luminescence. The effect of shell material on transport properties is measured. An AlGaN shell produces Ld values in excess of 1 μm and a relative insensitivity to wire diameter. An InGaN shell reduces effective diffusion length, while a dependence of Ld on diameter is observed for uncoated nanowires.