IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Semiconductors Tuesday Sessions
       Session SC-TuM

Paper SC-TuM5
InAs Surface Passivation for Electronics and Biosensors

Tuesday, October 30, 2001, 9:40 am, Room 124

Session: Semiconductor Interfaces and Thin Films
Presenter: D.Y. Petrovykh, University of Maryland, College Park
Authors: D.Y. Petrovykh, University of Maryland, College Park
M.J. Yang, Naval Research Laboratory
L.J. Whitman, Naval Research Laboratory
Correspondent: Click to Email
Many semiconductor-based chemical and biological sensors operate by detecting changes in the device conductivity caused by adsorption of organic or inorganic molecules on the sensor surface. The conductivity is affected by the surface charge induced by adsorbates, so sensors based on very thin films or nanostructures should be inherently more sensitive. InAs is a natural material for these applications, because the charge accumulation layer, naturally formed on its surface, provides intrinsic conductivity down to nm-scales. To be used in chemical/biological sensors, InAs films and nanostructures must be properly passivated and functionalized. Ammonium sulfide treatment, commonly used in GaAs processing, is known to effectively remove the oxide and other surface contaminants. We show that it also offers sub-5 nm etching, and the resulting S-passivated surface resists oxidation during short-term exposure to ambient air, or immersion in water (with a range of pH) or organic solvents. We will discuss the possibility of using alkanethiol films for longer-term stability and surface functionalization, including the use of selective deposition by dip-pen nanolithography. For sensor applications, it is also important to control the surface Fermi level pinning. We use conductivity measurements and electron spectroscopy to examine band bending in InAs films and the effects on the conductivity of different capping layers, passivation treatments and other common device processing steps. @FootnoteText@ This work was carried out at the Naval Research Laboratory and supported by the Office of Naval Research, National Nanotechnology Initiative Program on the Nanoscience Basis for Miniaturized, Intelligent Sensors.