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 TiO2 (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 (Dit) 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 Dit 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. © 1998 Elsevier Science Ltd. All rights reserved.