Semiconductor in equilibrium, Electrical Engineering

Assignment Help:

Semiconductor in Equilibrium

Equilibrium in semiconductors implies the following:

(i) Steady state: ∂Z / ∂t = 0

In which Z is any physical quantity like charge, voltage electric field etc.

(ii) No net thermal Currents and electrical current:

Because current can be carried via both electrons and holes, equilibrium involves zero values for both of the net electron current and net hole current. The drift and diffusion components of electron and hole currents require not be zero.

(iii) Constant Fermi energy:  dEF / dX = 0

The only one equations that are relevant (another being zero!) for analysis in equilibrium are:

Poisson Equation:

2Ψ0 / ∂x2 = - q/ε (p0 - n0 + ND+ - NA-)

n0 = ni exp (EF - Ei / KT)

P0 = ni exp (Ei - EF / KT)

n0 p0 = n2i                

In equilibrium, there is only single independent variable out of the three variables:  

n0, p0, Ψ0

If one of them is well known, all the rest can be measured from the equations listed above. We shall consider this independent variable to be potential. The analysis trouble in equilibrium is hence determination of potential or equivalently, energy band diagram of the semiconductor device. This is the cause why we begin discussions of all semiconductor devices with a sketch of the energy band diagram of it in equilibrium.


Related Discussions:- Semiconductor in equilibrium

Application of electrochemical grinding, Explain the working principle, Sur...

Explain the working principle, Surface finish, material removal, accuracy,advantages and application of Electrochemical Grinding(ECG). (a) In electro chemical machining of pure

Installation of meters and verification of connections, Installation of Met...

Installation of Meters and Verification of Connections Apart from testing and calibrating the meters they must be properly installed as per the links diagram. The points in wh

Formation of energy bands in solids, Describe in brief the Formation of ene...

Describe in brief the Formation of energy bands in solids and hence explain how it helps to classify the solid in to conductors and insulators. Energy Bands in Solids Acco

Find the initial current when switch is closed - capacitor, 1. In the circ...

1. In the circuit shown below, the capacitor initially has a voltage across it 4 Volts (at t = 0). a. Write down the expression for V C (t) when the switch is closed. b. Wr

Explain the fixed bias circuit, Q. Explain the fixed bias circuit?     ...

Q. Explain the fixed bias circuit?           The Fig refers to the common emitter collector characteristics and the ac and dc load lines.The Fig shows the points Q 1 and Q 2

permanent magnet stepper motor - stepper motor , Normal 0 fa...

Normal 0 false false false EN-IN X-NONE X-NONE   Permanent   Magnet Stepper Motor The s

Determine the speed at which the machine runs as a motor, A 100-kW, dc shun...

A 100-kW, dc shunt generator, connected to a 220-V main, is belt-driven at 300 r/min, when the belt suddenly breaks and the machine continues to run as a motor, taking 10 kW from t

Tri state devices, Tri State Devices Tri  State  devices have three  st...

Tri State Devices Tri  State  devices have three  states logic 1  logic  0 and high  impedance. A tri state device ( Buffer/ Inverter) has three  lines output  enable as shown

Congestion, It is uneconomic to provide adequate equipment to carry all the...

It is uneconomic to provide adequate equipment to carry all the traffic which could possibly be offered to a telecommunication system. In a telephone exchange it's theoretically po

Find the value of frequency, Although the low side is not as good a choice ...

Although the low side is not as good a choice as the high-side local oscillator frequency, let an AM broadcast receiver be designed with a low-side local oscillator. As fc is varie

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd