Impurity incorporation in epitaxially laterally overgrown GaN detected by cryogenic photoluminescence microscope with sub-micron spatial resolution

Abstract

Impurity incorporation from a SiO 2 mask in epitaxially laterally overgrown (ELO) GaN was depicted using a newly developed cryogenic scanning photoluminescence (PL) microscope. Both plan-view and cross-sectional PL images with a spatial resolution of 0.3 μm were obtained for emissions ascribed to free excitons (E XA) and excitons bound to donors (D 0X) at 15 K. In the cross-sectional μ-PL images, a bright emission of D 0X was observed in the area adjacent to the SiO 2 mask within a distance of approximately 8 μm from the mask, indicating an enhanced incorporation of donors such as Si atoms during the lateral growth. In the area beyond 8 μm from the mask, the D 0X emission was suppressed, showing a decrease in the donor incorporation after coalescence of ELO GaN on the SiO 2 mask.