Scanning tunneling optical spectroscopy of semiconductor quantum well structures

Scanning tunneling optical spectroscopy has been used to determine the optical properties of semiconductor quantum wells. With this technique, photoenhanced tunneling currents are measured with a scanning tunneling microscope on heterostructures illuminated with monochromatic light. For the InAs_xP_1-x/InP strained single quantum well structures, the 295 K spectra exhibit well-resolved transitions attributable to interband transitions involving the heavy-hole valence band and the n=1 conduction subband. The observed transition energies are in good agreement with values measured using photoconductivity and photoluminescence spectroscopy on the same samples.