Novel conductive transparent tip for low-temperature tunneling-electron luminescence microscopy using tip collection

Tip collection of luminescence is advantageous in low-temperature tunneling-electron luminescence microscopy because it can improve spatial resolution, luminescence collection yield, and thermal isolation. We have developed a novel conductive transparent (CT) tip that injects tunneling electrons into a sample and simultaneously collects tunneling-electron luminescence (TL). Essential features of the CT tip are a multimode fiber with a flame-shape tapered to a point, a gold-on-In2O3 double layer that serves as an optically transparent electrode to the apex, and a thick coaxial metal prating on the optical-fiber shaft that reinforces the CT tip allowing it to be firmly screwed onto a holder. The CT tip can easily be changed in a vacuum chamber like an air-metal tip. Using a TL microscope with the CT tip, TL spectra and TL images were successfully obtained on the cross section of GaAs(50 nm)/AlAs(50 nm) multiple quantum wells at 10 K. (C) 1997 American Vacuum Society.