Nanotechnology Now







Heifer International

Wikipedia Affiliate Button


DHgate

Home > Press > Hydrogen and inert species improve solid phase epitaxy of Ge on Si

(Color online) Comparison of Raman measurements of Ge layers deposited in vacuum (red, solid line) and deposited under N2 flux (blue, solid line with squares). For the vacuum deposited Ge layer, Ge–Ge stretch is observed, indicating the presence of structural ordering in the film. For the layer deposited under N2 flux no Ge–Ge stretch is visible, indicating complete disordering.
(Color online) Comparison of Raman measurements of Ge layers deposited in vacuum (red, solid line) and deposited under N2 flux (blue, solid line with squares). For the vacuum deposited Ge layer, Ge–Ge stretch is observed, indicating the presence of structural ordering in the film. For the layer deposited under N2 flux no Ge–Ge stretch is visible, indicating complete disordering.

Abstract:
Imec has shown that the presence of hydrogen and/or inert species during Ge deposition significantly improves the quality of the Ge layers grown on Si by solid phase epitaxy (SPE). The resulting layers have excellent crystalline quality and low surface roughness, making SPE a valuable alternative for conventional heteroepitaxy which is performed typically at much higher temperatures. High-quality Ge layers on Si are needed to explore the potential of Ge MOS devices for high-performance applications, or for extending conventional Si electronics.

Hydrogen and inert species improve solid phase epitaxy of Ge on Si

The Netherlands | Posted on April 21st, 2010

Imec has demonstrated that the presence of atomic hydrogen during Ge deposition at low temperatures favors the formation of smooth and high-quality Ge layers on Si by SPE. A similar observation is made when molecular hydrogen, molecular nitrogen or chemical inert atoms or molecules are added during deposition. This results in high-quality single-crystalline Ge layers with surface roughness of only 0.4nm root mean square. In absence of these species, Ge layers grown by SPE exhibit low crystalline quality. The availability of high-quality thin Ge layers on Si is indispensible for the research on Ge and Ge/III-V devices. Ge on Si can potentially replace Si CMOS for high-performance applications and extends conventional Si electronics for e.g. optoelectronic applications.

In case of SPE, an amorphous layer is deposited on a crystalline substrate using methods such as (plasma enhanced) chemical vapor deposition ((PE)CVD) or ultrahigh vacuum (UHV) deposition. Subsequent annealing of the structure initiates crystallization at the interface, which continues towards the surface. In this way, an epitaxial layer can be formed on the substrate. SPE allows straightforward deposition of Ge on Si. Conventional heteroepitaxial growth on the contrary requires additional steps in order to reduce surface roughness.

Typically, PECVD using germane (GeH4) molecules is used to deposit the initial amorphous Ge layer. In this case, atomic hydrogen is inherently present and can influence the crystallization process in many ways. Imec's research shows that atomic hydrogen plays an important role during Ge deposition as it lowers the surface mobility of adsorbed Ge atoms and consequently increases the disorder of the deposited layer. Such a disordered layer is highly beneficial for SPE where crystallization has to start at the interface before it starts in the bulk. Atomic hydrogen is also incorporated into the growing layer, but it does not affect the crystallization process. A similar explanation can be given when fluxes of H2, N2 or chemical inert species are added during deposition by UHV. They also reduce the surface mobility and thereby the structural ordering of the Ge layers. In contrast to atomic hydrogen, these atoms are not incorporated into the growing film. The Ge deposition is performed at low temperatures (typically 150°C), subsequent crystallization is done by thermal annealing at 600°C in an N2 atmosphere for one minute. Annealing temperatures as low as 400°C can be applied. The low temperatures present an important advantage with respect to conventional heteroepitaxy, which is typically performed at much higher temperatures.

Detailed results of this study have been published by R.R. Lieten et al in Applied Physics Letters 94, 2009, ‘Solid phase epitaxy of amorphous Ge on Si in N2 atmosphere' and in Applied Physics Letters 96, 2010, ‘Hydrogen and inert species in solid phase epitaxy'.

####

About imec
Imec is Europe’s largest independent research center in nanoelectronics and nano-technology. Its staff of more than 1,750 people includes over 550 industrial residents and guest researchers. Imec’s research is applied in better healthcare, smart electronics, sustainable energy, and safer transport.

For more information, please click here

Copyright © imec

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related News Press

News and information

Graphene Shows Promise In Eradication Of Stem Cancer Cells March 1st, 2015

Novel Method to Determine Optical Purity of Drug Components March 1st, 2015

Scientific breakthrough in rechargeable batteries: Researchers from Singapore and Québec Team Up to Develop Next-Generation Materials to Power Electronic Devices and Electric Vehicles February 28th, 2015

First detailed microscopy evidence of bacteria at the lower size limit of life: Berkeley Lab research provides comprehensive description of ultra-small bacteria February 28th, 2015

Possible Futures

European roadmap for graphene science and technology published February 25th, 2015

Quantum research past, present and future for discussion at AAAS February 16th, 2015

World’s first compact rotary 3D printer-cum-scanner unveiled at AAAS by NTU Singapore start-up: With production funded by crowdsourcing, the first unit will be delivered to the United States in March February 16th, 2015

Nanotechnology Electric Vehicle (EV) Market Analysis Report 2015: According to Radiant Insights, Inc February 13th, 2015

Chip Technology

New nanowire structure absorbs light efficiently: Dual-type nanowire arrays can be used in applications such as LEDs and solar cells February 25th, 2015

SUNY Poly CNSE Researchers and Corporate Partners to Present Forty Papers at Globally Recognized Lithography Conference: SUNY Poly CNSE Research Group Awarded Both ‘Best Research Paper’ and ‘Best Research Poster’ at SPIE Advanced Lithography 2015 forum February 25th, 2015

Ultra-thin nanowires can trap electron 'twisters' that disrupt superconductors February 24th, 2015

Silicon Catalyst Announces Partnership With imec to Support Semiconductor Start-Ups February 23rd, 2015

Nanoelectronics

New nanowire structure absorbs light efficiently: Dual-type nanowire arrays can be used in applications such as LEDs and solar cells February 25th, 2015

Ultra-thin nanowires can trap electron 'twisters' that disrupt superconductors February 24th, 2015

Improved fire detection with new ultra-sensitive, ultraviolet light sensor February 17th, 2015

Nanotechnology facility planned in Lund, Sweden: A production facility for start-ups in the field of nanotechnology may be built in the Science Village in Lund, a world-class research and innovation village that is also home to ESS, the European Spallation Source February 15th, 2015

Announcements

Graphene Shows Promise In Eradication Of Stem Cancer Cells March 1st, 2015

Novel Method to Determine Optical Purity of Drug Components March 1st, 2015

Scientific breakthrough in rechargeable batteries: Researchers from Singapore and Québec Team Up to Develop Next-Generation Materials to Power Electronic Devices and Electric Vehicles February 28th, 2015

First detailed microscopy evidence of bacteria at the lower size limit of life: Berkeley Lab research provides comprehensive description of ultra-small bacteria February 28th, 2015

Photonics/Optics/Lasers

Leti to Offer Updates on Silicon Photonics Successes at OFC in LA February 27th, 2015

Rice's Stephan Link honored for nanoscience research: The Welch Foundation honors ‘rising star’ with $100,000 Hackerman Award February 26th, 2015

Maximum Precision in 3D Printing: New complete solution makes additive manufacturing standard for microfabrication February 26th, 2015

Learning by eye: Silicon micro-funnels increase the efficiency of solar cells February 25th, 2015

NanoNews-Digest
The latest news from around the world, FREE




  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More










ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project







© Copyright 1999-2015 7th Wave, Inc. All Rights Reserved PRIVACY POLICY :: CONTACT US :: STATS :: SITE MAP :: ADVERTISE