Part 3: Heterojunctions - Bandgap Engineering E a

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Knowlton

MSE 510

Part 3: Heterojunctions - Bandgap Engineering

Bandgap Energy –vs- Lattice Constant

Red 700-630 nm; 1.77-1.97eV

Orange 630-600 nm; 1.97-2.07eV

Yellow 600-570 nm; 2.07-2.18eV

Green 570-520 nm; 2.18-2.38eV

Cyan 520-480 nm; 2.38-2.58eV

Blue 480-430 nm; 2.58-2.88eV

Violet 430-400 nm; 2.88-3.10eV

Alloy Ternary or Quaternary III-V to Adjust E g

& a: e.g., Al x

Ga

1-x

As or Ga x

In

1-x

N or Al

1-x-y

In x

Ga y

P

Knowlton Dr. Rod Nave, HyperPhysics, Georgia State University

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MSE 510

Part 3: Heterojunctions - Bandgap Engineering

Bandgap Energy –vs- Lattice Constant

Red 700-630 nm; 1.77-1.97eV

Orange 630-600 nm; 1.97-2.07eV

Yellow 600-570 nm; 2.07-2.18eV

Green 570-520 nm; 2.18-2.38eV

Cyan 520-480 nm; 2.38-2.58eV

Blue 480-430 nm; 2.58-2.88eV

Violet 430-400 nm; 2.88-3.10eV

Alloy Ternary or Quaternary III-V to Adjust E g

& a: e.g., Al x

Ga

1-x

As or Ga x

In

1-x

N or Al

1-x-y

In x

Ga y

P

Knowlton E.F. Schubert, Physical Foundations of Solid State Devices (2009)

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Knowlton

Knowlton

MSE 510

Part 3: Heterojunctions - Bandgap Engineering

Bandgap Energy –vs- Lattice Constant

Red 700-630 nm; 1.77-1.97eV

Orange 630-600 nm; 1.97-2.07eV

Yellow 600-570 nm; 2.07-2.18eV

Green 570-520 nm; 2.18-2.38eV

Cyan 520-480 nm; 2.38-2.58eV

Blue 480-430 nm; 2.58-2.88eV

Violet 430-400 nm; 2.88-3.10eV

Alloy Ternary or Quaternary III-V to Adjust E g

& a: e.g., Al x

Ga

1-x

As or Ga x

In

1-x

N or Al

1-x-y

In x

Ga y

P

Knowlton E.F. Schubert, Physical Foundations of Solid State Devices (2009)

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MSE 510

Part 3: Heterojunctions - Bandgap Engineering

Bandgap Energy –vs- Lattice Constant

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MSE 510

Heterojunctions - Bandgap Engineering

 III-V and II-VI Semiconductors

 Use for light emitting diodes, laser diodes and detectors (photon and other high energy particles)

II-VI

III-V

Knowlton

MSE 510

Bandgap Engineering Light Emitting Devices

Solid-state Semiconductor Lighting

The Gallium Nitride

Light Emitting Diode(LED):

200

 m

Knowlton

Completing the Visible

Spectrum from T. Sands, UC Berkeley

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MSE 510

Bandgap Engineering for Light Emitting Devices

 Bandgap Engineering: Quantum wells

 Note that the band offsets are not the same!

Knowlton V. Mitin, V. Kochelap, M. Stroscio, Quantum Heterostructures: Microelectronics and Optoelectronics , (Cambridge University Press, 2005) p. 412

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MSE 510

Bandgap Engineering for Light Emitting Devices

 Bandgap Engineering: Three types

 Note that the band offsets are not the same!

Type 1 Type 2 Type 3

Knowlton

Knowlton

Herbert Kroemer, Nobel Lecture: Quasielectric fields and band offsets: teaching electrons new tricks*, REVIEWS OF MODERN PHYSICS,

VOLUME 73, JULY 2001, *The 2000 Nobel Prize in Physics was shared by Zhores I. Alferov, Jack S. Kilby, and Herbert Kroemer. This lecture is the text of Professor Kroemer’s address on the occasion of the award.

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MSE 510

Here we will assume the band offsets are equal.

This is not usually the case.

E c

E f

E v

Heterojunctions – Type I

E vacuum

Band offset

E c

E f

E c

E f

E v

Flatband

Band offset

E v

p-type

(ex., GaAs)

n-type

(ex., AlN)

2DEG

(2d e e

-

-

Gas)

's

E c

E f

Chemical

Equilibrium

Band offset

E v

Knowlton

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MSE 510

Heterojunctions – Type I

Here we will assume the band offsets are equal.

This is not usually the case.

E

C

= Conduction Band offset

E c

E f

E c

E v

E

V

= Valence Band offset

n-type

(ex., GaAs)

p-type

(ex., GaN)

E f

E v

E vacuum

Flatband

E

C

E f

Chemical

Equilibrium

Band offset

E

V

Knowlton

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MSE 510

Other References

 Alfonso Franciosi and Chris G. Van de Walle, Heterojunction band offset engineering , Surface Science Reports 25 (1996) 1-140

Jasprit Singh, Electronic and Optoelectronic Properties of Semiconductor Structures

(Cambridge Press, 2003) Ch. 3 .2 p. 118

 V. Mitin, V. Kochelap, M. Stroscio, Quantum Heterostructures: Microelectronics and Optoelectronics , (Cambridge University Press, 2005)

 Anderson & Anderson, Fundamentals of Semiconductor Devices , (McGraw Hill,

2005) Ch. 6.3 p. 317-331

K.F. Brennan, The Physics of Semiconductors – with Applications to Optoelectronic

Devices , (Cambridge University Press, 1999) Ch. 11.2 p. 554

 Jasprit Sing, Physics of Semiconductors and Their Heterostructures, (McGraw Hill,

1993) Ch. 6

S.M. Sze, Physics of Semiconductor Devices , 2 nd Ed. (Wiley-Interscience, 1981)

 K.K. Ng, Complete Guide to Semiconductor Devices , 2 nd Ed. (Wiley-Interscience,

2002)

 Angus Rocket, , The Materials Science of Semiconductors , (Springer, 2007)

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