Nanoporous silicon doped by Cu for gas-sensing applications

• Published in: Physica. E, Low-dimensional systems & nanostructures Low-dimensional systems & nanostructures, 2007-04, Vol.38 (1), p.211-214
• Main Authors: Gorbanyuk, T.I., Evtukh, A.A., Litovchenko, V.G., Solntsev, V.S.
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Copper clusters; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Electronic transport in interface structures; Exact sciences and technology; General equipment and techniques; Hydrogen sulphide sensitivity; Instruments, apparatus, components and techniques common to several branches of physics and astronomy; Layered semiconductor MIS structures; Metal-insulator-semiconductor structures (including semiconductor-to-insulator); Nanoporous silicon doped by copper; Physics; Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing
• ISSN: 1386-9477; 1873-1759
• DOI: 10.1016/j.physe.2006.12.038

The effect of hydrogen sulphide on the current–voltage characteristics of metal–insulator–semiconductor (MIS) structures based on nanoporous silicon (Si nanopor) under copper doping has been investigated. Scanning electron (SEM), atomic force (AFM) and optic microscopes and/or secondary ion mass spectroscopy (SIMS) were used to obtain detailed characterisation of copper cluster distribution present at the surface and pores, respectively. SIMS spectra reveal that finite gradient in copper distribution along the pores and oxidation of nanoporous silicon simultaneously can be obtained successfully under electroless deposition process. It was also shown that the doping of nanoporous silicon by Cu leads to enhanced hydrogen sulphide sensitivity of MIS structures even without catalytic active top electrodes (for example, Pd) at room temperature. Furthermore, for different types of familiar MIS structures based on nanoporous silicon, e.g., MIS structures doped or undoped by copper and by using Pd metal electrodes, the hydrogen sulphide detection at room temperature mainly depends on the modification in the height of barrier of hetero- (Al–Cu–Si nanopor–c-Si) or Schottky-like (Pd–Cu–Si nanopor–c-Si) structures resulting the chemical interaction of molecular H 2S gas with copper clusters at the surface and in the pores. It is demonstrated that MIS structures based on the nanoporous silicon with copper doping are more sensitive to H 2S action at room temperature. In addition, the physical mechanism explaining the observed phenomena is also discussed.