Development of Dual-Probe Scanning Near-Field Optical Microscopy

Abstract

Dual-probe scanning near-field optical microscopy (DSNOM) is a useful nanoscopic tool to visualize local carrier motions. We developed a new DSNOM system with a novel distance control technique, which can independently control the sample-probe distance and the probe-probe distance. Thus, we applied it to the assessment of the carrier dynamics in a green-light-emitting InGaN single-quantumwell. It is clearly demonstrated that carriers anisotropically diffuse up to several hundred nanometers along a specific direction toward local potential minima showing a strong-photoluminescence domain because potential peaks cause carriers to travel a roundabout route around them. Moreover, we visualized the propagation of surface plasmon polaritons (SPPs) in a Ag waveguide structure, where twodimensional interference fringes are observed due to the multiple reflections at the side edges of a waveguide showing a wave character of SPPs.