MOSFET transistors, also known as metal-oxide-semiconductor field-effect transistors and metal-oxide-silicon transistors, are utilized for amplifying or switching circuit voltages. They are current-controlled electrical components equipped with three terminals called the Source, Gate, and Drain. The specific function of MOSFET transistors is to control the current flow of the Source and Drain, while the Gate applies to voltage.
MOSFET transistors are popularly used primarily because of their versatility. These components are used in analog and digital circuits, and often function as a power device. MOSFET transistors are a type of FET or field effect transistor; they are ideal for higher current applications.
These transistors are typically preferred over bipolar transistors because load-current control is possible even if there’s only a minimal current. Additionally, MOSFET transistors are compact in size, which is why it is easy to fabricate and design them into a single chip.
MOSFET transistors were invented in November 1959 at Bell Labs by Dawon Kahng and Mohamed M. Atalla. They were first publicly introduced in 1960. They are mass-produced and miniaturized for use in various applications and products including memory devices, microprocessors, digital wristwatch, and pocket calculators.
There are two types of MOSFET transistors: Enhancement and Depletion.
- Enhancement Type MOSFET transistors can be likened to a normally open switch. They need a VGS or Gate-Source voltage for the device switch to turn ON.
- Depletion Type MOSFET transistors are the opposite of Enhancement Types and therefore can be likened to a normally closed switch. The VGS is required to switch OFF the device
There are many other types of MOSFET transistors, including:
- NMOS Logic
- Complementary Metal-Oxide-Semiconductor or CMOS Logic
- PMOS Logic
- FGMOS or Floating-Gate MOSFETs
- MISFETs or Metal Insulator Semiconductor Field Effect Transistors
- Double-diffused Metal Oxide Semiconductors or DMOS
- Power MOSFETs
- RHBD (Radiation Hardened By Design)
- MOS Sensors
- Bipolar-MOS Transistors
- TFT (Thin-Film Transistor)
- MOS Capacitors
- Multi-Gate Field Effect Transistors