| Devices, Semiconductors, and Transistors
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| Device
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Type
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Material
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Application
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| Rectifiers (diodes)
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pn junction
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Silicon
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Low fwd. voltage drop, signal, and power rectification
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|
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pn junction
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Germanium
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high rectification ratio, high inverse breakdown, high temperature, signal and power rectification
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dry disc
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Selenium
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Power rectifier, low-frequency diode, self-healing
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|
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dry disc
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Copper oxide
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Meter rectifier, low voltage power rectifier
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dry disc
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Copper sulfide
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Low voltage power rectifier
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| Light Emitting Diode (LED)
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pn junction
pn junction
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Gallium arsenide
phosphide
Gallium indium
nitride
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Visible, infrared, light emitting, displays
Blue, green, and white light emitters
NOTE: LEDs with special properties have also been made of AlGaAs, AlGaP, AlGaInP, GaAs, GaP, SiC, and organic polymers (OLED).
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| Transistors (BJT)
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pnp or npn
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Germanium
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Low saturation voltage, general purpose to 75° C
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|
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pnp or npn
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Silicon
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High temp. use to 175° C, higher voltage
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| Field Effect Transistors (FET)
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n or p channel
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Silicon
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High input impedance, resistive, bidirectional output impedance
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| Unijunction Transistors
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n-type bar with p-junction be-tween ends of bar
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Silicon
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Relaxation oscillator, timing, trigger circuits, negative resistance device
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| Device
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Type
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Material
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Application
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|
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Thyristors:
Silicon Controlled Rectifier (SCR)
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pnpn
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Silicon
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Phase controlled rectifier, similar to thyratron tube
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| Triac
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two SCRs in parallel and opposite orientation
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Silicon
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Bidirectional control of AC, light dimmers, power tool speed control
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| Tunnel Diode
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pn (heavily doped)
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Germanium gallium arsenide
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Negative resistance, microwave amplifier, oscillators, converters
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Photo-diode
Photo-transistor
|
pn
npn
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Germanium
Silicon
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Photo-conduction and photo voltaic for control applications
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Photoelectric
Cells
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photo resistive
photo resistive
photo resistive
photo voltaic
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Lead sulfide
Lead telluride
Cadmium sulfide
Selenium
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Infrared detector
Infrared detector
Light meter
Light meter
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| Varistors
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fired
dry disc
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Silicon carbide
Selenium
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Surge suppressors
Contact protector
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| Device
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Type
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Material
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Application
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| Thermistors
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fired
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Mixed metal oxides
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Temperature sensing, control, compensating
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Varactor diodes
(varicap)
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pn junction
reverse biased
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Silicon
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Voltage controlled capacitor, parametric amplifier, multipliers
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| Zener diode
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pn junction
reverse breakdown
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Silicon
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Reverse biased, voltage regulator, voltage reference, noise source
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