Low-temperature Near-field Scanning Optical Microscope for UV-visible Spectroscopy of Nanostructures

Carl von Ossietzky Universit¨at Oldenburg, Institut fur¨ Physik, 26111 Oldenburg, Germany(Received 20 January 2010)A low-temperature near-field scanning optical microscope (LT-NSOM) is designed and realized inorder to study the optical properties of nanostructures at cryogenic temperatures in the UV-visiblewavelength range. Due to the simple and extensive optical design, any type of NSOM operationmode is accessible. In particular, the localized photoluminescence spectra of nanostructures can bemeasured at temperatures from 13 K up to 300 K. We successfully demonstrate the performance ofour LT-NSOM by investigating InGaN/GaN multiple quantum wells grown on a sapphire substrateat 15 K.