Tag: Semiconductor Devices
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Gunn Diode – Features, Operation & Applications
Features of a Gunn Diode A gunn diode is made up of only N-type semiconductor which is typically sandwiched between two metal conductors. The central section is usually lightly doped N– surrounded by heavily doped N+ layers. The central section is N-gallium arsenide whereas the two outer sections undergo epitaxial growth from GaAs with increased…
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Schottky Diode – Features & Applications
Schottky diode is fabricated as a metal-to-N junction rather than a P-N semiconductor junction. Also referred to as hot-carrier diodes, Schottky diodes are characterized by fast switching times (low reverse-recovery time), low forward voltage drop (normally 0.25 to 0.4 volts for a metal-silicon junction), and low junction capacitance. The forward voltage drop (VF), reverse-recovery time…
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The Shockley Diode Features & Operation
The Shockey diode is a four layer sandwich of PNPN semiconductor material very similar to the SCR but without a gate as illustrated in the Figure 1.0 below: The Operation of Shockley Diode A Shockley diode can be turned ON by applying enough voltage between anode and cathode. This voltage will cause one of the…
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Unijunction Transistor Features and Operation
The unijunction transistor (UJT) is a three terminal, single-junction device which exhibits negative resistance and switching characteristics totally unlike those of conventional bipolar transistors. The UJT consists of a bar of n-type having ohmic contacts designated Base 1 (B1) and Base 2 (B2) on either side of a single PN junction designated the emitter. An…
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The Junction Field Effect Transistors (JFET)
The bipolar transistor has several disadvantages: it has low input impedance because of forward biased emitter junction, it has small high-frequency gain, it has considerable noise level and it is non-linear when |VCE| < 2V. Although low input impedance problem may be improved by careful design and use or more than one transistor, even so…