Advanced InAs Quantum Well MOSFET: Device Bandgap Engineering and Hysteresis Effect
|關鍵字:||先進金氧半場效電晶體;砷化銦量子井金氧半場效電晶體;元件能隙工程;遲滯效應;高介電常數閘極介電質/金屬閘極;閥值電壓不穩定性;Advanced MOSFET;InAs Quantum Well MOSFET;Bandgap Engineering;Hysteresis Effect;High-k Gate Dielectric/Metal Gate;Threshold Voltage Instability|
This thesis focuses on two important issues in InAs quantum well MOSFETs: the bandgap engineering of the InGaAs/InAs/InGaAs composite channel as well as the hysteresis phenomena incurred by the interface states at the high-k/semiconductor interface. With respect to the device bandgap engineering, the influence of device epitaxial structures on carrier confinement and apparent mobility was firstly investigated by numerical simulations. The epitaxial structures used for the fabrication and characterization of the devices were introduced and reviewed. Through experimental verification, we found that optimized composite channel thickness and sub-channel indium (In) composition are beneficial to the drive current and the suppression of short channel effects. With respect to the hysteresis effect, we explored the physics origin and the bias dependences of hysteresis phenomena. A mechanism was proposed to explain the threshold voltage shift in hysteresis phenomena, and it was verified by experimental results. Various bias dependences were also studied and emphasized by using the derived equations. In addition, we also proposed a new method to extract the interface state density of the transistor without using MOS capacitor like conventional methods. The proposed method was able to evaluate the interface properties of the gate stack of MOS transistors. In addition, the physical models for the threshold voltage and gate capacitance of InAs quantum well MOSFETs were developed in order to have a understanding of the electrical behaviors of devices.
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