Tantalum nitride (TaN) films were prepared by reactive sputtering in a gas Ar and N2 for gate electrode applications. Resistivity, crystallinity, and work function of the films were investigated as a function of nitrogen flow rate. As the nitrogen flow rate increased from 0 to 20 sccm, the resistivity of as-deposited TaN films increased from 132 to 1.4×105 μΩ cm. With a nitrogen flow rate of 8 and 10 sccm, the fcc TaN phase was obtained. The work function of the TaN films was investigated using TaN-gated nmetal–oxide–semiconductor capacitors with SiO2 gate dielectrics of various thicknesses. As the nitrogen flow rate increased from 4 to 12 sccm, the work function decreased from 4.1 to 3.4 eV for as-deposited films. After annealing at 950 °C for 1 min, the work function increased to 4.5–4.7 eV, with less dependency on the nitrogen flow rate.
In this paper, we have analyzed the resistances (specific on-resistance and drain to source resistance) and transconductance of SiC MESFET. Source diffusion, channel, drift region, epi-layer and substrate resistances those contribute to the specific on-resistance have been analyzed. Effect of change in the junction depth due to post annealing on the implant range parameter is also considered. Half of change in the junction depth is added to the implant range parameter (before annealing). Straggle parameter is changed by diffusion coefficient and annealing time. Temperature dependency of mobility is also considered in all parameters. The variation of transconductance taking the drain to source voltage as a parameter has also been analyzed. Our analysis provides in-depth knowledge about the operation and characteristics of the high-power SiC MESFETs.
HfOz with EOT of 14A shows soft and hard breakdown behaviors which consist of different Weibull distributions, area scaling factors, and acceleration factors. Thickness dependence of Hf02 Weibull slope p indicates that the breakdown mechanism of Hf02 is intrinsic. Similar to SiOz, steeper voltage acceleration factor of HfO2 has been observed as thickness decreases. Unipolar AC voltage stress on MOS capacitors results in larger lifetime compared to constant voltage stress. This may be due to lower overall charge trapping as a result of short "on time" compared to the transition time and charge detrapping during the off period. The higher the frequency of the AC stress, the longer time-tobreakdown.
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