We report on thermal stability of the effective work function (EWF) of RuO2-rich Ru–Si–O gate electrodes intended for high-performance p-channel metal-oxide-semiconductor field-effect transistors. The Ru–Si–O thin films, with the composition 15% and 40% of SiO2, were grown by atomic vapor deposition at either 380 or 450°C on SiO2∕Si substrate. The Ru–Si–O thin film with 15% of SiO2 deposited at 450°C was evaluated as the most thermally stable gate electrode showing the EWF of 5.0eV after rapid thermal annealing (RTA) at 800°C∕10s in nitrogen followed by forming gas annealing (FGA). Transmission electron microscopy studies show that Ru–Si–O films are composed of RuO2-rich nanograins embedded in the SiO2-rich amorphous matrix. The Ru–Si–O films show enhanced thermal stability, as we observe reduction of RuO2 to Ru nanograins without disintegration of the layers after RTA at 900°C∕10s and subsequent FGA 430°C∕30min. Resistivity of the Ru–Si–O films as a function of temperature was found to be dependent on composition as well as deposition temperature. Resistivity of the Ru–Si–O film with 15% of SiO2 deposited at 450°C shows metalliclike character with a residual resistivity ratio of 1.3. The effect of RTA and FGA on the resistivity of the Ru–Si–O films is discussed in terms of the increase in connectivity and grain size.

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The well known Shockley-Read-Hall (SRH) model considers emission and capture processes at defects exhibiting a single level or multiple non-coupled levels in the band gap of the semiconductor. The present paper generalizes the model to the case of two mutually coupled defect levels acting as trapping centres. If the intercenter transition is not considered, the model reduces to the case of two non-coupled levels treated by the SRH model. THEORYThe paper considers the existence of lattice defects (electrically active traps) having two coupled defect levels (CDL) in the band gap of the semiconductor between which thermal exchange of free charge carriers takes place. The two coupled capture centres are denoted by indices a and b with corresponding energies E Our CDL model considers ten exchange processes of free charge carriers between the capture centres and the conduction and valence bands. These processes are schematically shown in Fig. 1.Each of the ten exchange processes (five capture and five emission processes) is characterized by its escape time. If the unknown occupation probability of a trapping centre is divided by the escape time of a capture process, or the probability of non-occupation by the escape time of an emission process, one obtains the frequency of the particular exchange process. The frequencies of exchange processes allow to build two equations with two unknown variables, the occupation probabilities of centres a and b. Their solution leads to a quadratic equation yielding finally the occupation probabilities. Then, in terms of the ten escape times and of the evaluated occupation probabilities of centres a and b one can correctly define the SRH and CDL recombination rates contained in the continuity equations [3]. The quasi-static continuity equations for electrons and holes can be written as 1 q dJ e

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