Photomicrograph of two metal-gate MOSFETs in a test pattern.

Nevertheless Kahng pointed out several advantages of the device, notably ease of fabrication and its application in integrated circuits. The device was about 100 times slower than contemporary bipolar transistors and was initially seen as inferior. The principles behind the device were the same as the ones that were tried by Bardeen, Shockley and Brattain in their unsuccessful attempt to build a surface field-effect device. Atalla showed that silicon dioxide is very effective in solving the problem of one important class of surface states.įollowing this Atalla and Dawon Kahng demonstrated a device that had the structure of a modern MOS transistor. Further research showed that silicon dioxide could prevent dopants from diffusing into the silicon wafer. Derick accidentally grew a layer of silicon dioxide over the silicon wafer. The structure failed to show the anticipated effects, due to the problem of surface state: traps on semiconductor the surface that hold electrons immobile. The structure resembling the MOS transistor was proposed by Bell scientists William Shockley, John Bardeen and Walter Houser Brattain, during their investigation that led to discovery of the transistor effect. The basic principle of this kind of transistor was first patented by Julius Edgar Lilienfeld in 1925. 8.7 Radiation-hardened-by-design (RHBD).8.6 Double-diffused metal-oxide-semiconductor (DMOS).8.3 Metal-insulator-semiconductor field-effect transistor (MISFET).3.1 Metal-oxide-semiconductor structure.Since MOSFETs can be made with either p-type or n-type semiconductors, complementary pairs of MOS transistors can be used to make switching circuits with very low power consumption, in the form of CMOS logic. The MOSFET is by far the most common transistor in digital circuits, as billions may be included in a memory chip or microprocessor.

Similarly, 'oxide' in the name can also be a misnomer, as different dielectric materials are used with the aim of obtaining strong channels with smaller applied voltages. The 'metal' in the name MOSFET is sometimes a misnomer, because the gate material can be a layer of polysilicon (polycrystalline silicon). In depletion mode transistors, voltage applied at the gate reduces the conductivity. In an enhancement mode MOSFET, voltage applied to the gate terminal increases the conductivity of the device. The main advantage of a MOSFET is that it requires almost no input current to control the load current, when compared with bipolar transistors (bipolar junction transistors/BJTs). Operating as switches, each of these components can sustain a blocking voltage of 120 V in the off state, and can conduct a continuous current of 30 A in the on state, dissipating up to about 100 W and controlling a load of over 2000 W. Two power MOSFETs in D2PAK surface-mount packages.

Fet electronics