MOS transistor

John A. Copeland and Stephen Knight, Applications Utilizing Bulk Negative Resistance F.A. Padovani, The Voltage-Current Characteristics of Metal-Semiconductor Contacts P.L. Hower, W.W. Hooper, B.R. Cairns, R.D. Fairman, and D.A. Tremere, The GaAs Field-Effect Transistor Marvin H. White, MOS Transistors... 

Fig.4.17. Cross-section of a microhotplate with integrated MOS-transistor heater, D and S denote drain and soiu ce of the transistor...

Replacing the respective variables in Eq. (4.3) using the Eqs. (4.5), (4.6), (4.7) and (4.8), a temperature-dependent MOS transistor model is obtained. This temperature-dependent model provides a term for the source-drain current depending on the source-gate voltage, the source-drain voltage, and the temperature. 

Fig. 4.20. Comparison between measured Zsd-versus- T characteristics of the MOS transistor and the MOS-transistor model results for a source-drain voltage of 5 V...

The relative deviation between measurement results and the temperature-depen-dent MOS transistor model data was less than 10% above 100 °C. In the case of a source-drain bias of 5 V it appeared that the model described the real situation well up to 300 °C, but then started to deviate. 

The third microhotplate design included a MOS-transistor heater embedded in a silicon island (Sect. 4.4). One advantage of this configuration is the reduction of the... 

The last and most advanced system presented in this book includes an array of three MOS-transistor-heated microhotplates (Sect. 6.3). The system relies almost exclusively on digital electronics, which entailed a significant reduction of the overall power consumption. The integrated C interface reduces the number of required wire bond connections to only ten, which allows to realize a low-prize and reliable packaging solution. The temperature controllers that were operated in the pulse-density mode showed a temperature resolution of 1 °C. An excellent thermal decoupling of each of the microhotplates from the rest of the array was demonstrated, and individual temperature modulation on the microhotplates was performed. The three microhotplates were coated with three different metal-oxide materials and characterized upon exposure to various concentrations of CO and CH4. 

S. Muller. CMOS-Micro-Hotplate with MOS Transistor Heater for Integrated Metal Oxide Gas Sensors, Diploma thesis, ETH Zurich, Switzerland (2002). 

MOSFETs. The metal-oxide-semiconductor field effect transistor (MOSFET or MOS transistor) (8) is the most important device for very-large-scale integrated circuits, and it is used extensively in memories and microprocessors. MOSFETs consume little power and can be scaled down readily. The process technology for MOSFETs is typically less complex than that for bipolar devices. Figure 12 shows a three-dimensional view of an n-channel MOS (NMOS) transistor and a schematic cross section. The device can be viewed as two p-n junctions separated by a MOS capacitor that consists of a p-type semiconductor with an oxide film and a metal film on top of the oxide. 

Understanding the behavior of a MOS capacitor is useful in understanding the operation of a MOS transistor. When a negative voltage is applied to the conductor or metal, the energy bands in the p-type semiconductor... 

NMOS and PMOS (p-channel MOS) transistors are used side by side in complementary metal-oxide-semiconductor (CMOS) technology to form logic elements. These structures have the advantage of extremely low power consumption and are important in ultralarge-scale integration (ULSI) and very-large-scale integration (VLSI) (13). 

Figure 14. Schematics of MOS transistors. lD denotes the drain current. (Reproduced with permission from reference 8. Copyright 1985 Wiley.)...

Example NMOS Fabrication. The individual steps listed in List I can be sequenced to give a simple process for the fabrication of an NMOS transistor (Figures 12 and 15) Although the example is a MOS transistor, the techniques also apply to the fabrication of bipolar transistors, diodes, capacitors, resistors, and ICs. 

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