Mapping quantum-well energy profiles of III-V heterostructures by scanning-tunneling-microscope-excited luminescence

A technique has been developed that allows the energy profile of quantum wells in ${\mathrm{Al}}_{\mathit{x}}$ ${\mathrm{Ga}}_{1\mathrm{-}\mathit{x}}$As heterostructures to be mapped directly. The lateral resolution is a few nanometers, which allows the band-bending profile and the conduction-band discontinuity of interfaces within the heterostructure to be probed directly. The technique is based on the excitation of luminescence in the III-V compounds using the tip of a scanning tunneling microscope as a source of electrons.