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ECE 4339 L. Trombetta ECE 4339: Physical Principles of Solid State Devices Len Trombetta Summer 2007 Chapter 15: FET Introduction: The JFET and MESFET Goal: To understand this figure. Slide 2 ECE 4339 L. Trombetta Before we look at device operation, lets look at a few examples of FET technology JFET Slide 3 ECE 4339 L. Trombetta MOSFET: Metal-Oxide-Semiconductor FET Dynamic Random Access Memory (DRAM) cell: a MOS transistor coupled with a MOS capacitor Slide 4 ECE 4339 L. Trombetta Charge Coupled Device (CCD). This device is used to get images in many digital cameras. A variation, called CMOS imaging, is used in low-end cameras. Slide 5 ECE 4339 L. Trombetta Complementary MOS (CMOS) is a low-power, high density digital logic technology. It is the basis of most modern integrated circuits, including high- performance microprocessors Slide 6 ECE 4339 L. Trombetta Modulation-doped FET (MODFET). These are fabricated from III-V devices for high speed. 2-dimensional electron gas (2-DEG) forms the channel in a low-doped region for high mobility. Slide 7 ECE 4339 L. Trombetta Slide 8 Slide 9 Slide 10 Slide 11 V G is the same across the channel, but there is an additional potential, V(y), which is a function of y: V(0) = 0 and V(L) = V D in the figure. Thus the depletion depth is Note that V G is negative and V(y) is positive, so W increases with an increase in either one. Slide 12 ECE 4339 L. Trombetta Slide 13 Slide 14