ELECTRONIC-PROPERTIES OF THIN AU NANOPOROUS-SI/N-SI STRUCTURES/

Ultrathin nanoporous Si layers (UPSL) were prepared on n-Si(100) by an odization in aqueous NH4F solution starting from an electrochemically hydrogenated surface. The thickness of the UPSL was controlled with fi eld emission scanning electron microscopy, The interface state density (D-it) of UPSL was measured with a field-dependent pulsed surface pho tovoltage technique. The value of D-it, normalized to the surface area of UPSL is about 1.3 x 10(11) eV(-1) cm(-2). Au/UPSL/n-Si structures were characterized with temperature-dependent current-voltage measurem ents. The room-temperature barrier height and the ideality factor at t he Au/UPSL interface were 0.75 eV and 1.8, respectively. The temperatu re dependence of the reverse current of Au/UPSL/n-Si structures showed two regions with activation energies at 120 meV and about 60 meV for temperatures below and above 200 K, respectively. Strong near-infrared electroluminescence was observed for Au/UPSL/n-Si structures. The res ults are discussed on the basis of the role of Si nanostructure surfac e conditioning with regard to the porous Si electronic properties.