Near‐field spectroscopy of single quantum dots at room temperature

Abstract

The observation of photoluminescence spectra of self-assembled single InGaAs quantum dots at room temperature was performed under weak excitation conditions using a near-field scanning optical microscope. Operation in illumination-collection mode with a highly sensitive double-tapered optical fibre probe enabled detection of weak photoluminescence signals at room temperature with high efficiency and high spatial resolution. Each single quantum dot was imaged with a spatial resolution of about 250 nm, which corresponded to a quarter of the wavelength of the photoluminescence from quantum dots. The photoluminescence yields of individual quantum dots were widely distributed and were found to decrease with photoluminescence energy. This result serves as a clue to be pursued for better understanding of the thermal excitation of the carrier from confined states in quantum dots.

Development of Aperture-Type Near-Field Reflection Spectroscopy and Its Application to Single Silver Nanoplates

“…In aperture-type SNOM, near-field reflection measurements can be performed under illumination–collection (IC) mode, where the illumination and collection of light are both carried out by the aperture of the near-field probe. ,,− Therefore, the near-field reflection microscope under IC mode allows one to obtain genuine near-field characteristics of samples . One of the major drawbacks of IC mode arises from the spatial overlap of the signal and the large background.…”