The effect of hydrogen-induced interface traps on a titanium dioxide-based palladium gate MOS capacitor (pd-mosc) : A conductance study

Abstract The conductance versus gate voltage response of a palladium-gate MOS capacitor with 0.5 μm of TiO 2 (oxide layer) has been studied as a function of hydrogen gas concentration and signal frequency. The structure of the device was completed by evaporating titanium dioxide over p 〈111〉-type silicon wafer (cleaned as per standard silicon technology) having a resistivity of 3–5 Ω cm and subsequent palladium front with aluminium back metallization. The G - V response of the fabricated MOS capacitor was studied on exposure to hydrogen in Ar ambient. The fabricated device is sensitive to hydrogen (1–3%) at room temperature. The interface state density ( D it ) was determined at the surface potential corresponding to the peak in the conductance curve, using a bias scan conductance method at fixed frequency. It was found that D it increases with an increase in hydrogen gas concentration. Further, it has been observed that a change in conductance is better at lower frequencies, which may be due to the balanced communication of interface traps with the valance and conduction bands of silicon substrate.

[1]  H. Geistlinger.  The influence of chemisorption on the defect equilibrium of metal oxide thin films , 1996 .

[2]  Toshimasa Matsuoka,et al.  A study on a palladium-titanium oxide Schottky diode as a detector for gaseous components , 1980 .

[3]  I. Lundström,et al.  Chemical reactions on palladium surfaces studied with Pd-MOS structures , 1977 .

[4]  Ingemar Lundström,et al.  Hydrogen sensitive mos-structures: Part 1: Principles and applications , 1981 .

[5]  S. K. Srivastava,et al.  A titanium dioxide-based MOS hydrogen sensor , 1990 .

[6]  B. Lalevic,et al.  Transition metal-gate MOS gaseous detectors , 1982, IEEE Transactions on Electron Devices.

[7]  G. J. Maclay,et al.  The effect of hydrogen and carbon monoxide on the interface state density in MOS gas sensors with ultra-thin palladium gates , 1990 .

[8]  F. Bregani,et al.  Temperature effects on the size of anatase crystallites in MoTiO2 and WTiO2 powders , 1996 .

[9]  C. Nylander,et al.  Hydrogen‐induced oxide surface charging in palladium‐gate metal‐oxide‐semiconductor devices , 1984 .

[10]  S. M. Sze,et al.  Physics of semiconductor devices , 1969 .

[11]  I. Lundström,et al.  Hydrogen sensitivity of palladium--thin-oxide--silicon Schottky barriers , 1976 .

[12]  Submonolayer-Pt on TiO2 (110) Surfaces: Electronic and Geometric Effects , 1996 .

[13]  Y. Nakato,et al.  Mechanism of hydrogen sensing by platinum/silicon oxide/silicon MIS tunneling diodes , 1994 .

[14]  Role and mechanism of the formation of hydrogen-induced interface states for platinum/silicon oxide/silicon MOS tunnelling diodes , 1995 .

[15]  Hikaru Kobayashi,et al.  Reactions of hydrogen at the interface of palladium-titanium dioxide Schottky diodes as hydrogen sensors, studied by workfunction and electrical characteristic measurements , 1994 .

[16]  B. Flietner,et al.  Dipole- and charge transfer contributions to the work function change of semiconducting thin films: experiment and theory , 1996 .

[17]  Hikaru Kobayashi,et al.  MECHANISM OF THE FORMATION OF HYDROGEN-INDUCED INTERFACE STATES FOR PT/SILICON OXIDE/SI METAL-OXIDE-SEMICONDUCTOR TUNNELING DIODES , 1995 .