<title>Local optical characteristics of semiconductor surfaces</title>

Abstract

Photoluminescence (PL), photoreflectance (PR) and photocurrent (PC) spectroscopic techniques have demonstrated to be helpful experimental methods to investigate the properties of bulk semiconductors, microstructures, surfaces and interfaces. We present near-field local PL, PR and PC spectroscopic study of semiconductor quantum structures using a technique of reflection Scanning Near-field Optical Microscope (SNOM) in combination with Nitrogen laser and tuning dye laser and with He-Ne laser. Reflection Scanning Near-field Optical Microscope (SNOM) employs an uncoated and/or Au-metallized single-mode fiber tip both as nanosource and a nanoprobe. In the illumination-collection hybrid mode, the first one serves to excite the semiconductor sample and the second one to investigate characteristics of the structure and to pick up the PL and PR intensity reflected from the sample. In the illumination mode, the nanosource illuminates locally the semiconductor structure, and excites the photoelectrons in the PC spectroscopy. This near-field device is applied for the diagnostics of the defects in semiconductor devices. Take opportunity of the high lateral resolution of the microscope and combine it with fast micro-PL, PR responses, it is possible to locate for instance defects in a multiple quantum well grown by molecular beam epitaxy. Near-field characteristics of measured quantities are also discussed.