Download - Silicon Quantum Dots: Grown by Ion Implantation and annealing By Mary Coan.

Silicon Quantum Dots: Grown by Ion Implantation and

annealing

By

Mary Coan

Outline• History of Silicon quantum dots

– How they were made

• Properties of Silicon Quantum Dots grown by ion implantation and annealing

• Advantages/Disadvantages

• Different methods to grow Silicon Quantum Dots– Which method is the best?

• Summary

History of Si QDs

• 1960’s: First quantum size effects were seen in semiconductor nanocrystals

• 1970’s: Louis Brus was working in Bell Labs researching colloidal synthesizes

• 1980’s: First semiconductor quantum dots were grown

• 1990: First visible-photoluminescence seen from Si QDs

History of Si QDs

• 1993: Silicon optoelectronic integrated circuit is suggested

• 1993 to present: Si Quantum dots have been extensively researched– Different fabrication methods

• microwave plasma decomposition of SiH4• laser breakdown of SiH4• plasma-enhanced chemical vapor deposition• high frequency discharge• high dose ion implantation

Formation of Si QDs: Ion implantation and annealing

T.S. Iwayama, T. Hama, D.E. Hole, I.W. Boyd, Vacuum 81, 179 (2006).

Properties of Si QDs

• Photoluminescence– Peak energy and intensity

• Size ranges from 1 nm to over 10 nm in diameter

• Size distribution within host material

Photoluminescence

C.W. White, J.D. Budai, S.P. Withrow, J.G. Zhu and S.J. Pennycock, IEEE Conference Proceeding 824 (1996).

Photoluminescence


Suggested Mechanisms

T.S. Iwayama, T. Hama, D.E. Hole, I.W. Boyd, Solid-State Electronics 45, 1487 (2001).

Suggested Mechanisms

R. Krishnan, UR, (2005).

Range of Sizes

• Longer anneals = Larger Si QDs– Ostwald Ripening


Size distribution within Host Material

M.L. Brongersma, A. Polman, K.S. Min, H.A. Atwater, “J. Appl. Phys. 86, 759 (1999).

Defects within Host

C. J. Nicklaw, M. P. Pagey, S. T. Pantelides, D. M. Fleetwood, R. D. Schrimpf, K. F. Galloway, J. E. Wittig, B. M. Howard, E. Taw, W. H. McNeil, J. F. Conley, Jr., IEEE Trans. Nucl. Science 47, 2269 (2000).

Advantages/Disadvantages

• Advantages:– Ease of integration into silicon based

microelectronics (Dots and Process)– Ability to control the PL intensity and peak

energy

• Disadvantages:– Large size distribution within host material– Defects within host material– Surface damage (QDs)

Other Fabrication Techniques

• Microwave Plasma Decomposition of Silane Gas

• Laser breakdown of Silane Gas

• Plasma Enhanced Chemical Vapor Deposition

• High Frequency Spark Discharge

• Colloidal

Which Method is Best?

• It depends on what you want to use the Silicon QDs for.

• If you want to make an optoelectical integrated circuit:– Plasma Enhanced CVD– Ion Implantation

• If you want some cool flourishing Si QDs:– Colloidal

Summary

• Properties of Si QDs were discussed– PL dependent on:

• Anneal time, temperature and process• Ion dose

• Defects caused by Ion Implantation– Quantum dot surface\host material

• Causing lower luminescence intensity

– A Large size distribution throughout the Host

• In the past this was a good technique now it is outdated by PCVD

Questions ??