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Mercury Cadmium Telluride: Growth, Properties and Applications



Mercury Cadmium Telluride: Growth, Properties and Applications


Mercury cadmium telluride (MCT) is the third most well-regarded semiconductor after silicon and gallium arsenide and is the material of choice for use in infrared sensing and imaging. The reason for this is that MCT can be ‘tuned’ to the desired IR wavelength by varying the cadmium concentration.

Mercury Cadmium Telluride: Growth, Properties and Applications provides both an introduction for newcomers, and a comprehensive review of this fascinating material. Part One discusses the history and current status of both bulk and epitaxial growth techniques, Part Two is concerned with the wide range of properties of MCT, and Part Three covers the various device types that have been developed using MCT. Each chapter opens with some historical background and theory before presenting current research. Coverage includes:

  • Bulk growth and properties of MCT and CdZnTe for MCT epitaxial growth
  • Liquid phase epitaxy (LPE) growth
  • Metal-organic vapour phase epitaxy (MOVPE)
  • Molecular beam epitaxy (MBE)
  • Alternative substrates
  • Mechanical, thermal and optical properties of MCT
  • Defects, diffusion, doping and annealing
  • Dry device processing
  • Photoconductive and photovoltaic detectors
  • Avalanche photodiode detectors
  • Room-temperature IR detectors
Series Preface



List of Contributors

Part One - Growth

1 Bulk Growth of Mercury Cadmium Telluride (MCT)

P. Capper

1.1 Introduction

1.2 Phase Equilibria

1.3 Crystal Growth

1.4 Conclusions


2 Bulk growth of CdZnTe/CdTe crystals

A. Noda, H. Kurita and R. Hirano

2.1 Introduction

2.2 High-purity Cd and Te

2.3 Crystal Growth

2.4 Wafer processing

2.5 Summary



3 Properties of Cd(Zn)Te (relevant to use as substrates)

S. Adachi

3.1 Introduction

3.2 Structural Properties

3.3 Thermal Properties

3.4 Mechanical and Lattice Vibronic Properties

3.5 Collective Effects and Some Response Characteristics

3.6 Electronic Energy-band Structure

3.7 Optical Properties

3.8 Carrier Transport Properties


4 Substrates for the Epitaxial growth of MCT

J. Garland and R. Sporken

4.1 Introduction

4.2 Substrate Orientation

4.3 CZT Substrates

4.4 Si-based Substrates

4.5 Other Substrates

4.6 Summary and Comclusions


5 Liquid phase epitaxy of MCT

P. Capper

5.1 Introduction

5.2 Growth

5.3 Material Characteristics

5.4 Device Status

5.5 Summary and Future Developments


6 Metal-Organic Vapor Phase Epitaxy (MOVPE) Growth

C. M. Maxey

6.1 Requirement for Epitaxy

6.2 History

6.3 Substrate Choices

6.4 Reactor Design

6.5 Process Parameters

6.6 Metalorganic Sources

6.7 Uniformity

6.8 Reproducibility

6.9 Doping

6.10 Defects

6.11 Annealing

6.12 In-situ monitoring

6.13 Conclusions


7 MBE growth of Mercury Cadmium Telluride

J. Garland

7.1 Introduction

7.2 MBE Growth theory and Growth Modes

7.3 Substrate Mounting

7.4 In-situ Characterization Tools

7.5 MCT Nucleation and Growth

7.6 Dopants and Dopant Activation

7.7 Properties of MCT epilayers grown by MBE

7.8 Conclusions


Part Two - Properties

8 Mechanical and Thermal Properties

M. Martyniuk, J.M. Dell and L. Faraone

8.1 Density of MCT

8.2 Lattice Parameter of MCT

8.3 Coefficient of Thermal Expansion for MCT

8.4 Elastic Parameters of MCT

8.5 Hardness and deformation characteristics of HgCdTe

8.6 Phase Diagrams of MCT

8.7 Viscosity of the MCT melt

8.8 Thermal properties of MCT


9 Optical Properties of MCT

J. Chu and Y. Chang

9.1 Introduction

9.2 Optical Constants and the Dielectric Function

9.3 Theory of Band-to-band Optical Transition

9.4 Near Band Gap Absorption

9.5 Analytic Expressions and Empirical Formulas for Intrinsic Absorption and Urbach Tail

9.6 Dispersion of the Refractive Index

9.7 Optical Constants and Related van Hover Singularities above the Energy Gap

9.8 Reflection Spectra and Dielectric Function

9.9 Multimode Model of Lattice Vibration

9.10 Phonon Absorption

9.11 Raman Scattering

9.12 Photoluminescence Spectroscopy


10 Diffusion in MCT

D. Shaw

10.1 Introduction

10.2 Self-Diffusion

10.3 Chemical Self-Diffusion

10.4 Compositional Interdiffusion

10.5 Impurity Diffusion


11 Defects in HgCdTe – Fundamental

M. A. Berding

11.1 Introduction

11.2 Ab Initio calculations

11.3 Prediction of Native Point Defect Densities in HgCdgTe

11.4 Future Challenges


12 Band Structure and Related Properties of HgCdTe

C. R. Becker and S. Krishnamurthy

12.1 Introduction

12.2 Parameters

12.3 Electronic Band Structure

12.4 Comparison with Experiment



13 Conductivity Type Conversion

P. Capper and D. Shaw

13.1 Introduction

13.2 Native Defects in Undoped MCT

13.3 Native Defects in Doped MCT

13.4 Defect Concentrations During Cool Down

13.5 Change of Conductivity Type

13.6 Dry Etching by Ion Beam Milling

13.7 Plasma Etching

13.8 Summary


14 Extrinsic Doping

D. Shaw and P. Capper

14.1 Introduction

14.2 Impurity Activity

14.3 Thermal Ionization Energies of Impurities

14.4 Segregation Properties of Impurities

14.5 Traps and Recombination Centers

14.6 Donor and Acceptor Doping in LWIR and MWIR MCT

14.7 Residual Defects

14.8 Conclusions


15 Structure and electrical characteristics of Metal/MCT interfaces

R. J. Westerhout, C. A. Musca, Richard H. Sewell, John M. Dell, and L. Faraone

15.1 Introduction

15.2 Reactive/intermediately reactive/nonreactive categories

15.3 Ultrareactive/reactive categories

15.4 Conclusion

15.5 Passivation of MCT

15.6 Conclusion

15.7 Contacts to MCT

15.7 Surface Effects on MCT

15.8 Surface Structure of CdTe and MCT


16 MCT Superlattices for VLWIR Detectors and Focal Plane Arrays

James Garland

16.1 Introduction

16.2 Why HgTe-Based Superlattices

16.3 Calculated Properties

16.4 Growth

16.5 Interdiffusion

16.6 Conclusions



17 Dry Plasma Processing of Mercury Cadmium Telluride and related II- VIs

Andrew Stolz

17.1 Introduction

17.2 Effects of Plasma Gases on MCT

17.3 Plasma Parameters

17.4 Characterization – Surfaces of Plasma Processed MCT

17.5 Manufacturing Issues and Solutions

17.6 Plasma Processes in Production of II-VI materials

17.7 Conclusions and Future Efforts


18 MCT Photoconductive Infrared Detectors

I. M. Baker

18.1 Introduction

18.2 Applications and Sensor Design

18.3 Photoconductive Detectors in MCT and Related Alloys

18.4 SPRITE Detectors

18.5 Conclusions on Photoconductive MCT Detectors



Part Three – Applications

19 HgCdTe Photovoltaic Infrared Detectors

I. M. Baker

19.1 Introduction

19.2 Advantages of the Photovoltaic Device in MCT

19.3 Applications

19.4 Fundamentals of MCT Photodiodes

19.5 Theoretical Foundations for MCT Array Technology

19.6 Manufacturing Technology for MCT Arrays

19.7 Towards “GEN III” Detectors

19.8 Conclusions and Future Trends for Photovoltaic NCT Arrays


20 Nonequilibrium, dual-band and emission devices

C. Jones and N. Gordon

20.1 Introduction

20.2 Nonequilibrium Devices

20.3 Dual-Band Devices

20.4 Emission devices

20.5 Conclusions


21 HgCdTe Electron Avalanche Photodiodes (EAPDs)

I. M. Baker and M. Kinch

21.1 Introduction and Applications

21.2 The Avalanche Multiplication Effect

21.3 Physics of MCT EAPDs

21.4 Technology of MCT EAPDs

21.5 Reported Performance of Arrays of MCT EAPDs

21.6 Laser-gated Imaging as a Practical Example of MCT EAPDs

21.7 Conclusions and Future Developments


22 Room-temperature IR photodetectors

Jozef Piotrowski and Adam Piotrowski

22.1 Introduction

22.2 Performance of Room-Temperature Infrared Photodetectors

22.3 MCT as a Material for Room-Temperature Photodetectors

22.4 Photoconductive Devices

22.5 Photoelectromagnetic, Magnetoconcentration and Dember IR Detectors

22.6 Photodiodes

22.7 Conclusions