| Summary: | 碩士 === 國立臺灣大學 === 電機工程學研究所 === 90 === In this thesis, the metal gate MOS diode and photodetector, diffusion length measurement of lightly doped silicon, Ge quantum dot photodetector, and air-bridge inductor are investigated.
First, because of not suffering depletion effects and providing for low gate sheet resistance, metals provide advantages over poly-Si for gate-electrode application, The performances of different metal gate electrodes are demonstrated. The post metal anneal effect, temperature effect, illumination effect for I-V, C-V characteristics and workfunction of different metal gate electrodes are also investigated.
The direct tunneling electron current from Al electrode to n-type silicon is the main component of the photocurrent, which is one order of magnitude larger than minority generation current in the deep depletion region. The two plateaus in the I-V curves of the photocurrent are the signatures of these two mechanisms. The direct tunneling hole current in the NMOS is very small, and only the minority (electron) generation current forms the photocurrent.
The lifetime τ and the diffusion length L of non-equilibrium carriers are the main parameters that characterize the quality of Si as semiconductor material. By measuring the dark current and photocurrent of devices for lightly doped p-type silicon and solving the equation that let the photo-generated current ratio equal to the effective area ratio, a novel method has been presented to determine and measure the minority carrier diffusion length. The main advantage of this method is its simple, easy, rapid, and cheap analyses and measurement.
Silicon dioxide dots are deposited on Si cap layer of self-assembled Ge dots by using a liquid phase deposition (LPD) method. Even through the components of Ge quantum dots are different in layers and spacers, the dark current of Schottky Barrier detector is higher than LPD and RTO oxide detectors. The efficiency of Schottky Barrier detector is higher than LPD oxide detector and RTO oxide detector in general. Also the efficiency of three Ge quantum dot photodetectosr under 1.3 or 1.5 μm lightwave exposure are extracted and compared.
A scalable physical model that can accurately predict the behavior of inductors with different structural parameters over a broad range of frequency would be a valuable RF IC design tool. The effect of layout geometry is investigated by simulation, and the larger Cs, Rs, Cox, and Csi will result in the smaller Q-values. At frequency well below the peak in the inductor Q, the inductor Q increases with frequency. However, as the operation frequency continues to rise, the Q-factor reaches peaks and then decreases.
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