Near field optical spectroscopy of resonant tunnelling light-emitters

Optical spectroscopy of resonant tunneling light-emitters has yielded relevant information on the charge and electric-field distribution in and across these devices but due to far-field collection of the light-emission, local intensity or field distributions could not be measured. We have carried out collection-mode near-field scanning optical microscopy of resonant tunneling light emitting devices and the intensity distribution of the near-field reveals electric field inhomogeneities across the optical window. In addition, the near-field spectra show the lateral electric field distribution from the quantum-confined Stark effect. Field variations of 15 kV cm−1 across the optical window of 70 μm devices were measured. Routine analysis of spectral lineshapes from the spatially-averaged far-field spectra therefore introduces significant error solved only by the use of local probing.