ALL INDIA SENIOR SCHOOL

CERTIFICATE EXAMINATION
(AISSCE)

Session: 2024-25
SHIRDI SAI PUBLIC SCHOOL, MORADABAD
PHYSICS PROJECT FILE
Topic: Analytical Study of Drift Velocity in the Low
Dimensional Devices
Submitted To
Central Board of Secondary Education
Submitted By Supervised By

Amandeep Singh XII A Mrs. Alpana Singh

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 Certificate
It is hereby to certify that, the original and
genuine investigation work has been carried out
to investigate about the subject matter and the
related data collection and investigation has
been completed solely, sincerely and
satisfactorily by AMANDEEP SINGH of class
XII A, SHIRDI SAI PUBLIC SCHOOL,
MORADABAD regarding his project titled
“ANALYTICAL STUDY OF DRIFT
VELOCITY IN THE LOW DIMENSIONAL
DEVICES”.
Teacher’s Name: Mrs. Alpana Singh
Teacher’s Signature:___________

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 Acknowledgement
It would be my utmost pleasure to express my
sincere thanks to my physics teacher Mrs.
Alpana Singh in guiding and providing a
helping hand in this project. Her valuable
advice, support and supervision all through this
project titled “ANALYTICAL STUDY OF
DRIFT VELOCITY IN THE LOW
DIMENSIONAL DEVICES”, are responsible
for attaining its present form.
Amandeep Singh
XII-A (Science)

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 INDEX

S. Topic Page
No. No.
1. Introduction
 Drift velocity
Explanation
 Objective
 Apparatus
 Theory
 Data Analysis
 Diagrams
 Conclusion
 Precautions
2. Important note
3. Bibliography

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 Introduction
Drift velocity is the average velocity that a charged particle such as an electron attains

due to an electric field. In low-dimensional devices , such as nanowires , quantum dots ,

and graphene sheets , the behavior of drift velocity can be significantly different from

that in bulk materials due to quantum confinement effects , surface scattering , and

other factors .

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OBJECTIVE

To understand the concept of drift velocity, And to study the factors affecting

Drift velocity in low dimensional devices, Also to analyze how low

Dimensionality alters the drift velocity compared to bulk materials.

APPARATUS

 Low dimensional materials like graphene sheets, nanowires , or quantum dots.

 Semiconductor parameter analyzer for measuring current-voltage characteristics.

 Source-meter unit for applying electric fields and measuring currents.

 Microscope for imaging low-dimensional structures.

THEORY

The drift velocity of electrons in a conductor is defined as the product of the

mobility of the charge carriers and the electric field applied across the conductor.

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The SI unit of drift velocity is m/s. Drift refers to the slow movement towards a

Thing / object. Every material above absolute zero temperature which can conduct

Like metals will have some free electrons moving at random velocity. When a

Potential is applied across a conductor the electrons will tend to move towards

The positive potential, but as they move, they will collide with atoms and will

Bounce back or lose some of their kinetic energy. However, due to the electric

Field, the electrons will accelerate back again, and these random collisions will

Keep happening but as the acceleration is always in the same direction due to

The electric field, the net velocity of the electrons will also be in the same

Direction.

MOBILITY:

Mobility is the measure of how quickly an electron can move through a

Semiconductor when subjected to an electric field. It is influenced by factors like

Temperature, impurities, and the structure of the material.

LOW-DIMENSIONAL DEVICES:

1. Quantum Dots:

They are the zero dimensional structures where electrons are confined in all

Three spatial dimensions.

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2. Nanowires:

They are the one dimensional structures with confinement in two

dimensions.

3. Graphene:

They are the two dimensional structures with confinement in one

dimension.

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FACTORS AFFECTING DRIFT VELOCITY IN
LOW-DIMENSIONAL DEVICES:

1. Quantum Confinement:

 When the dimensions of the device are comparable to the de

Broglie wavelength of the electrons, quantum confinement effects

become significant, altering the energy levels and band structure of

the material. It is responsible for the increase of energy difference

between energy states and band gap.

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2. Surface Scattering:

 In low dimensional materials, surface scattering can dominate over

Bulk scattering mechanisms, affecting the mobility and hence the

Drift velocity. It is the inelastic scattering of the coherent

Oscillating electrons at the particle surface. It results in reduction

of electrical conductivity.

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3. Phonon Scattering:

 Interaction with lattice vibrations (phonons) can be different in low

Dimensional structures due to altered phonon spectra, impacting

Electron mobility. In this electronic relaxation or energy transfer

occurs between the warm (thermalized) electrons and lattice phonons.

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4. Electrostatic Effects:

 In nanoscale devices, electrostatic interactions become more

pronounced, influencing the charge distribution and Drift velocity.

It is an effect that relates to an electric field or is created by an

Electric charge.

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DATA ANALYSIS

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 1. Current-Voltage(I-V) Characteristics:

 Plot the I-V curves for both low-dimensional and bulk samples.

 Determine the slope to find the conductance.

2. Mobility Calculation:

 From the I-V data, find the value of mobility.

3. Drift Velocity:

 Calculate the drift velocity for different applied electric fields

And compare the results for low-dimensional and bulk samples.

DIAGRAMS

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CONCLUSION

The implications of observed differences in drift velocity between low-dimensional

And bulk materials are:

1. Device Performance: High mobility and drift velocity are generally desirable

For high-speed and high-frequency applications. In low-dimensional devices

Optimizing these parameters is crucial for achieving superior performance.

2. Material Choice: Different materials techniques can significantly impact

Mobility and drift velocity. For example, graphene exhibits exceptionally

High mobility due to its unique electronic properties, making it attractive

For low-dimensional electronic devices.

3. Temperature Dependence: Both mobility and drift velocity are temperature

Dependent and this dependence can be more pronounced in low-dimensional

Systems . Understanding and controlling these dependences is important for

Reliable device operation across different temperatures.

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PRECAUTIONS

1. Temperature Control: Maintain a stable temperature throughout the experiment,

As mobility and carrier concentration can be temperature dependent.

2. Minimize Contact Resistance: Ensure that the contacts (electrodes) on the

Device are ohmic and have low resistance.

3. Stable and uniform electric field: Apply a uniform electric field across the

Device.

4. Avoid high electric fields: Keep the electric field low enough to avoid

Heating effects and nonlinear behavior. And also ensure that the electric

Field is within the linear regime of the I-V characteristics to maintain

Ohm’s law validity.

5. Clean environment: Conduct the experiment in a clean environment to

Minimize contamination and defects. Also use cleanroom facilities if possible

To avoid dust and other contaminants.

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IMPORTANT NOTE

This study will provide valuable insights into the unique electronic properties of

Low-dimensional devices and their potential applications in future technologies .

BIBLIOGRAPHY

www.google.com
www.wikipedia.com
www.scribd.com
www.slideshare.net

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