SOLID STATE DEVICESSOLID STATE DEVICESPOWERPOINT PRESENTATION ONPOWERPOINT PRESENTATION ON

PROJECT REPORTPROJECT REPORTSubmitted in partial fulfillment of the Submitted in partial fulfillment of the

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BACHELOR OF SCIENCESBACHELOR OF SCIENCESInIn

PHYSICSPHYSICS

SUBMITTED BY:RAJNI TRIPATHI

TALKFLOW

• Solid state devices – Introduction.• P and N type Materials.• PN Junction.• Diode and its types.• Transistor and its types.• Integrated circuits.• Advantages of Solid State

Devices.

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What Are SOLID STATE DEVICES Made Out Of?

• Silicon (Si) and Germanium (Ge) are the two most common single elements that are used to make Diodes.

• Silicon and Germanium are both group 4 elements, meaning they have 4 valence electrons.

• Their structure allows them to grow in a shape called the diamond lattice.

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N-Type Material

•When extra valence electrons are introduced into a material such as silicon an n-type material is produced. •The extra valence electrons are introduced by putting impurities or dopants into the silicon. •The dopants used to create an n-type material are Group V elements. •The most commonly used dopants from Group V are arsenic, antimony and phosphorus. •The extra electron is very mobile.

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P-Type Material

•P-type material is produced when the dopant that is introduced is from Group III. •Group III elements have only 3 valence electrons and therefore there is an electron missing. •This creates a hole (h+), or a positive charge that can move around in the material. •Commonly used Group III dopants are aluminum, boron, and gallium.•This hole is quite mobile in the same way the extra electron is mobile in a n-type material.

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The PN JunctionSteady State

When no external source is connected to the pn junction, diffusion and drift balance each other out for both the holes and electrons

Space Charge Region: Also called the depletion region. This region includes the net positively and negatively charged regions. The space charge region does not have any free carriers. The width of the space charge region is denoted by W in pn junction formula’s.

Metallurgical Junction: The interface where the p- and n-type materials meet.

Na & Nd: Represent the amount of negative and positive doping in number of carriers per centimeter cubed. Usually in the range of 1015 to 1020.

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The Biased PN Junction

PP nn++__

Applied Electric Applied Electric FieldField

Metal Metal ContactContact““Ohmic Ohmic Contact”Contact”(Rs~0)(Rs~0)

++ __

VVappliedapplied

II

The pn junction is considered biased when an external voltage is applied. There are two types of biasing: Forward bias and Reverse bias. These are described on then next slide.

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The Biased PN Junction

Forward Bias:Forward Bias:In forward bias the depletion region shrinks slightly in width. With this shrinking the energy required for charge carriers to cross the depletion region decreases exponentially. Therefore, as the applied voltage increases, current starts to flow across the junction. The barrier potential of the diode is the voltage at which appreciable current starts to flow through the diode. The barrier potential varies for different materials.

Reverse Bias:Reverse Bias: Under reverse bias the depletion region widens. This causes the electric field produced by the ions to cancel out the applied reverse bias voltage. A small leakage current, Is (saturation current) flows under reverse bias conditions. This saturation current is made up of electron-hole pairs being produced in the depletion region. Saturation current is sometimes referred to as scale current because of it’s relationship to junction temperature.

VVappliedapplied > 0 > 0

VVappliedapplied < 0 < 0

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Types of Diodes and Their Uses

PN Junction PN Junction Diodes:Diodes: Are used to allow current to flow in one direction while

blocking current flow in the opposite direction.

Schematic Symbol for a PN Schematic Symbol for a PN Junction DiodeJunction Diode

Representative Structure for a PN Representative Structure for a PN Junction DiodeJunction Diode

Zener Diodes:Zener Diodes: Are specifically designed to operate under reverse breakdown conditions. These diodes have a very accurate and specific reverse breakdown voltage..

Schematic Symbol for a Zener Schematic Symbol for a Zener DiodeDiode

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Types of Diodes and Their Uses

Schottky Diodes:Schottky Diodes: These diodes are designed to have a very fast switching time which makes them a great diode for digital circuit applications. They are very common in computers because of their ability to be switched on and off so quickly.

Shockley Diodes:Shockley Diodes: The Shockley diode is a four-layer diode while other diodes are normally made with only two layers. These types of diodes are generally used to control the average power delivered to a load.

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Types of Diodes and Their Uses

Light-Emitting Light-Emitting Diodes:Diodes:

Light-emitting diodes are designed with a very large bandgap so movement of carriers across their depletion region emits photons of light energy. Lower bandgap LEDs (Light-Emitting Diodes) emit infrared radiation, while LEDs with higher bandgap energy emit visible light. Many stop lights are now starting to use LEDs because they are extremely bright and last longer than regular bulbs for a relatively low cost.

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Types of Diodes and Their Uses

Photodiodes:Photodiodes: While LEDs emit light, Photodiodes are sensitive to received light. They are constructed so their pn junction can be exposed to the outside through a clear window or lens.In Photoconductive mode the saturation current increases in proportion to the intensity of the received light. This type of diode is used in CD players.In Photovoltaic mode, when the pn junction is exposed to a certain wavelength of light, the diode generates voltage and can be used as an energy source. This type of diode is used in the production of solar power.

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Transistors

• A Transistor is an semiconductor which is a fundamental component in almost all electronic devices.• Transistors are often said to be the most significant invention of the 20th Century.• Transistors have many uses including switching, voltage/current regulation, and amplification - all of which are useful in renewable energy applications.

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Function of Transistors

• Transistors amplify current, for example they can be used to amplify the small output current from a logic chip so that it can operate a lamp, relay or other high current device. In many circuits a resistor is used to convert the changing current to a changing voltage, so the transistor is being used to amplify voltage.

• A transistor may be used as a switch (either fully on with maximum current, or fully off with no current) and as an amplifier (always partly on).

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Types of Transistors

•There are two types of standard transistors, NPN and PNP, with different circuit symbols.•The letters refer to the layers of semiconductor material used to make the transistor.•The leads are labeled base (B), collector (C) and emitter (E).15

•Integrated Circuits are usually called ICs and popularly known as

a silicon chip, computer chip or microchip.

•It is usually combined with other components to form a more complex

system.

Integrated Circuits

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• Several hundred identical integrated circuits (ICs) are made at a time on a thin wafer several centimeters wide, and the wafer is subsequently sliced into individual ICs called chips.

IC Fabrication

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• SSI (small-scale integration): Up to 100 electronic components per chip

• MSI (medium-scale integration): From 100 to 3,000 electronic components per chip

• LSI (large-scale integration): From 3,000 to 100,000 electronic components per chip

• VLSI (very large-scale integration): From 100,000 to 1,000,000 electronic

components per chip

• ULSI (ultra large-scale integration): More than 1 million electronic components per

chip

IC Types

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• Digital integrated circuits can contain anything from one to millions of logic

gates, flip-flops, multiplexers, and other circuits in a few square millimeters.

• The small size of these circuits allows high speed, low power dissipation, and

reduced manufacturing cost compared with board-level integration.

• These digital ICs, typically microprocessors, DSPs, and micro controllers, work

using binary mathematics to process "one" and "zero" signals.

Digital Integrated Circuits

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• Analog ICs, such as sensors, power management circuits,

and operational amplifiers, work by processing continuous signals.

• They perform functions like amplification, active

filtering, demodulation, and mixing.

Analog Integrated Circuits

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Mixed Integrated Circuits

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1. Extremely small size—thousands times smaller than discrete circuit. It is because of fabrication of various circuit elements in a single chip of semi-conductor material.

2. Very small weight owing to miniaturized circuit.

3. Very low cost because of simultaneous production of hundreds of similar circuits on a small semiconductor wafer. Owing to mass production an IC costs as much as an individual transistor.

4. More reliable because of elimination of soldered joints and need for fewer inter-connections.

5. Low power consumption because of their smaller size.

Advantages of Solid State Devices

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6. Easy replacement as it is more economical to replace them than to repair them.

7. Increased operating speeds because of absence of parasitic capacitance effect.

8. Close matching of components and temperature coefficients because of bulk production in batches.

9. Improved functional performance as more complex circuits can be fabricated for achieving better characteristics.

10. Greater ability of operating at extreme temperatures.

Advantages of Solid State Devices

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References :

• Google• www.Authorstream.com

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THANKYOU

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