1)SEMICONDUCTOR DEVICES 2)WORKING PRINCIPLE OF DIODE AND SPECIAL DIODE Birla Vishwakarma Mahavidyalaya Branch: Electronics and Telecommunication Branch code: 11, Semester: 03 Subject: Electronic Devices and Circuits Subject code: NAME & ENROLMENT NO. YOGESH IYER( ) NISHANT KUMAR( ) PARV JOSHI( ) KARNAV PANWALA( )

Semiconductor device Semiconductor device, electronic circuit component made from a material that is neither a good conductor nor a good insulator (hence semiconductor). Such devices have found wide applications because of their compactness, reliability, and low cost. As discrete components, they have found use in power devices, optical sensors, and light emitters, including solid-state lasers.light Semiconductor device have high conductivities, typically from 10 4 to 10 6 Siemens per centimeter. The conductivities of semiconductors are between these extremes.

Semiconductor devices are as follows: P-N Junction diode BJT

P – N Junction diode P-N Junction diodes are formed when a P type semiconductor and N type semiconductor are sandwiched together.

Types of Diodes Zener diode Photo diode LED Tunnel diode Schottky diode Varicap

Transistor a semiconductor device, having three or more terminals attac hed to electrode regions, in which current flowing between two electrodes is controlled by a voltage or current applied to one or more specified electrodes. The device is capable of a mplification,etc, and has replaced the valve in most circuits si nce it is much smaller, more robust, and works at a much low er voltage.

V-I Characteristics

Semiconductor Devices Semiconductor devices don't follow ohms law(V=IR) As the temperature increases the conductivity of the device increases and resistivity decreases. At high temp mobility of electron in these devices is very high(µ=V/E)

Working principle of P-N junction diode P n NaNd Space Charge Region ionized acceptors ionized donors E-Field ++__ h+ drift h+ diffusion e- diffusion e- drift ==

Types of Diodes and Their Uses PN Junction Diodes: Are used to allow current to flow in one direction while blocking current flow in the opposite direction. The pn junction diode is the typical diode that has been used in the previous circuits. AK Schematic Symbol for a PN Junction Diode Pn Representative Structure for a PN Junction Diode Zener Diodes: Are specifically designed to operate under reverse breakdown conditions. These diodes have a very accurate and specific reverse breakdown voltage. AK Schematic Symbol for a Zener Diode

Varactor Diode Varactor is a type of p-n junction diode that operates in reverse bias. The capacitance of the junction is controlled by the amount of reverse bias. Varactor diodes are also referred to as varicaps or tuning diodes and they are commonly used in communication systems...1 Basic Operation The capacitance of a reverse-biased varactor junction is found as: Reverse-biased varactor diode acts as a variable capacitor. Varactor diode symbol where, C = the total junction capacitance. A = the plate area. ε = the dielectric constant (permittivity). d = the width of the depletion region (plate separation). (-1) Special Diode

Optical Diodes There are two popular types of optoelectronic devices: light-emitting diode (LED) and photodiode..4.1 The Light-Emitting Diode (LED) LED is diode that emits light when biased in the forward direction of p-n junction. AnodeCathode The schematic symbol and construction features. (b)(c) Special Diode

Application The seven segment display is an example of LEDs use for display of decimal digits. The 7-segment LED display. Special Diode

The Photodiode Photodiode is a p-n junction that can convert light energy into electrical energy. It operates in reverse bias voltage (V R ), as shown where I λ is the reverse light current. It has a small transparent window that allows light to strike the p-n junction. The resistance of a photodiode is calculated by the formula as follows: Special Diode

Other Types of Diodes The Schottky Diode A Schottky diode symbol is shown The Schottky diode’s significant characteristic is its fast switching speed. This is useful for high frequencies and digital applications. It is not a typical diode in that it does not have a p-n junction. Instead, it consists of a doped semiconductor (usually n-type) and metal bound together, as shown in Fig. Schottky diode symbol and basic internal construction of a Schottky diode. Special Diode

The Laser Diode The laser diode (light amplification by stimulated emission of radiation) produces a monochromatic (single color) light. Laser diodes in conjunction with photodiodes are used to retrieve data from compact discs. Basic laser diode construction and operation. Special Diode

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