Unit cell design cross section

Figure 6.8 shows a simplified cross section of a unit cell of a 4H-SiC power BJT. The cell pitch, P, is given hy the sum of width of the emitter mesa, width of the p base implant, and the total base-to-emitter spacings. An example of the device layout is shown in Figure 6.9. The goal of unit cell design is to minimize the cell pitch, since most of the current flows along the sidewalls of emitter mesas. It is important to maximize the density of emitter mesa sidewall density without compromising the performance of the transistor.

Fig. 2 (a) Face view of a representative bipolar plate (elements are not necessarily shown to actual scale), (b) Cross-section view of a representative unit cell design (elements are not necessarily shown to actual scale). MEA membrane/electrode assembly... 

Design. Sizing of dissolved gas flotation units is based on a hydraulic loading in gpm/sq ft of cross sectional area of the cell. Sport reported using a value of 2.0 gpnvsq ft for full pressurization systems, and 4.0 gpm/sq ft for recycle systems.1... 

Our research work in electrophoretic extraction has confirmed the technical feasibility of multistage extraction of cells using electric fields. However, a good amount of research needs to be done to bring the ADSEP to the market as ELECSEP (electrophoretic separator). For example, immediate study is required to examine the efficacy of the unit for the fractionation of mixtures of cells. Prehminary experiments have indicated that the resolution is being hampered by the depth of the chamber. So in the future design the depth of the chamber is to be reduced while increasing the diameter/cross sectional area of the chambers. 

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