Nanotechnology Now

Our NanoNews Digest Sponsors



Heifer International

Wikipedia Affiliate Button


android tablet pc

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

Novel approach to magnetic measurements atom-by-atom October 1st, 2014

Nanoparticles Accumulate Quickly in Wetland Sediment: Aquatic food chains might be harmed by molecules "piggybacking" on carbon nanoparticles October 1st, 2014

'Stealth' nanoparticles could improve cancer vaccines October 1st, 2014

Stressed Out: Research Sheds New Light on Why Rechargeable Batteries Fail October 1st, 2014

Possible Futures

Air Force’s 30-year plan seeks 'strategic agility' August 1st, 2014

IBM Announces $3 Billion Research Initiative to Tackle Chip Grand Challenges for Cloud and Big Data Systems: Scientists and engineers to push limits of silicon technology to 7 nanometers and below and create post-silicon future July 10th, 2014

Virus structure inspires novel understanding of onion-like carbon nanoparticles April 10th, 2014

Local girl does good March 22nd, 2014

Chip Technology

Graphene chips are close to significant commercialization October 1st, 2014

Speed at its limits September 30th, 2014

Research mimics brain cells to boost memory power September 30th, 2014

'Pixel' engineered electronics have growth potential: Rice, Oak Ridge, Vanderbilt, Penn scientists lead creation of atom-scale semiconducting composites September 29th, 2014

Nanoelectronics

Grenoble Hosting SEMICON Europa Oct. 7-9, First Time Event Held in France: Leti’s 90-square-meter Booth Will Feature Portable Showroom To Demonstrate New Technology Innovations September 24th, 2014

SouthWest NanoTechnologies (SWeNT) Receives NIST Small Business Innovation Research (SBIR) Phase 1 Award to Produce Greater than 99% Semiconducting Single-Wall Carbon Nanotubes September 19th, 2014

Rice rolls 'neat' nanotube fibers: Rice University researchers' acid-free approach leads to strong conductive carbon threads September 15th, 2014

Excitonic Dark States Shed Light on TMDC Atomic Layers: Berkeley Lab Discovery Holds Promise for Nanoelectronic and Photonic Applications September 11th, 2014

Announcements

'Stealth' nanoparticles could improve cancer vaccines October 1st, 2014

Stressed Out: Research Sheds New Light on Why Rechargeable Batteries Fail October 1st, 2014

New Absorber Will Lead to Better Biosensor: Biosensors are more sensitive and able to detect smaller changes in the environment October 1st, 2014

Graphene chips are close to significant commercialization October 1st, 2014

Photonics/Optics/Lasers

New Absorber Will Lead to Better Biosensor: Biosensors are more sensitive and able to detect smaller changes in the environment October 1st, 2014

Speed at its limits September 30th, 2014

'Pixel' engineered electronics have growth potential: Rice, Oak Ridge, Vanderbilt, Penn scientists lead creation of atom-scale semiconducting composites September 29th, 2014

Southampton scientists grow a new challenger to graphene September 23rd, 2014

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 1999-2014 7th Wave, Inc. All Rights Reserved PRIVACY POLICY :: CONTACT US :: STATS :: SITE MAP :: ADVERTISE