Near-field photoreflectance spectroscopic studies of semiconductor quantum well structures

Abstract

We present near-field photoreflectance (NPR) spectroscopic studies of GaAs/Al0.3Ga0.7As quantum well structures using near-field scanning optical microscope with either all uncoated or a metal-coated tapered optical fiber probe. The pump and probe beams are coupled into a single-mode fiber tip using a 2 x 2 fiber coupler, so that both the pump and probe beams are automatically overlapped and focused onto the same sample position. The NPR experiments are, carried out ill illumination-collection mode as a function of excitation intensity and tip-to-sample distance. The NPR technique demonstrated in this work call be used as a complementary tool that probes wore information about higher energy states in various quantum structures.