Ge MOSFETs
Silicon technology is all pervasive and underpins the IT revolution that is now reshaping society. The technology keeps improving year on year as chip sizes are being continually reduced and transistor speeds increase. One way to improve the speed of transistors, and in particular that of p-channel devices, is to replace the silicon in the conducting channel with germanium. Holes (and electrons) in Ge have a higher mobility than in the corresponding Si devices so can accelerate faster, and this can be further enhanced by straining the Ge crystal. Up to now using Ge has been a compromise as the leakage current is much greater than in Si; however, by producing the structure “on-insulator” (grown on an oxide substrate rather than on bulk Si) this leakage can be reduced and greater control of the channel is possible.
At Warwick we have a collaboration with the advanced technology institute IMEC (in Belgium) to produce strained Ge-on-insulator platforms and measure the electrical properties of devices processed on these platforms. Germanium, in at the birth of the electronics revolution, is experiencing a renaissance as a semiconductor material – and is attracting huge interest as the silicon end-game hots up. It is perceived as a potential candidate which will maintain CMOS technology and associated devices well beyond the end of silicon and also take the technology into new territories and performance regimes. This project sets out to explore some of the intriguing aspects and consequences of its band structure not previously examined – carrier mobilities, effective masses and scattering processes associated with unconventional crystallographic orientations and channel directions and in various states of strain. Exotic CVD growth and processing techniques will be used to realize two-dimensional (2D) electron and hole gases and the carrier transport properties will be investigated over a wide temperature range. Germanium is also being recognised as having tremendous potential in 1D and 0D and the fundamental studies proposed here would be a precursor to more wide-ranging investigations of low dimensional phenomena. Three UK groups with international reputations and who are uniquely positioned to undertake this research will carry out the work and the participation of IMEC, the leading European nano-processing laboratory, will give us unparalleled access to tools not otherwise available in the UK.
Project details
| Sponsor | EPSRC EP/F031408/1 |
| Title | Renaissance Germanium |
| Dates | Jan. 2009 to June 2012 |
Project Outcomes
Strained germanium layers were grown epitaxially on silicon substrates, with much higher quality than previously achieved, using an industrially compatible technique. The project enabled many advances of the growth technique (RP-CVD) to be explored and world leading material to be produced.
Key findings were:
- The first ever strained Ge MOSFETs were fabricated with 65nm gate lengths on silicon (100) substrates. There is now very considerable interest in Ge as a transitor material, but this was the first invastigation of strained layers with high-k dielectric gates.
- The highest mobility germanium 2D hole gases were formed, with hole mobility of over 1,000,000 cm^2/Vs, which is an order of magnitude improvement on previous work. This was made possible by the ultra clean growth environment and elimination of impurities in the material. These structures show the fractional quantum Hall effect in Ge for the first time.
- Growth of relaxed germanium on non-standard orientation silicon substrates (111) and (110) was demonstrated and improved by an order of magnitude in terms of smoothness and threading dislocation density (TDD). The (111) layers were sufficiently smooth for device quality material to be contemplated, which had previously been dismissed as a possibility.
Links to collaborators
Publications from this project:
1.1 A. Dobbie, R.J.H. Morris, A.H.A. Hassan, M.J. Prest, J. S. Richardson-Bullock, V.A. Shah, E.H.C. Parker, T.E. Whall, M. Myronov and D.R. Leadley
Ultra-High Hall Mobility of One Million in a Two-Dimensional Hole Gas in a Strained Germanium Quantum Well
Applied Physics Letters (submitted June 2012)
1.2 A. Dobbie, Van Huy Nguyen, M. Myronov and D.R. Leadley
Smooth, low defect germanium layers grown on (111) silicon by reduced pressure chemical vapour deposition
Applied Physics Express 5 071301 (2012)
1.3 A. Dobbie, Van Huy Nguyen, R.J.H. Morris, Xue-Chao Liu, M. Myronov and D.R. Leadley
Thermal Stability of Thin Compressively Strained Ge Surface Channels Grown on Relaxed Si0.2Ge0.8 Reverse-Graded Buffers
Journal of Electrochemical Society 159 H490-496 (2012)
1.4 C. Riddet, J.R. Watling, K-H. Chan, E.H.C. Parker, T.E. Whall, D.R. Leadley and A. Asenov
Hole Mobility in Germanium as a Function of Substrate and Channel Orientation, Strain, Doping and Temperature
IEEE Transactions on Electron Devices (accepted Feb 2012)
1.5 K. Gallacher, P. Velha, D.J. Paul, I. MacLaren, M. Myronov, and D.R. Leadley
Ohmic Contacts to n-type Germanium with Low Specific Contact Resistivity
Applied Physics Letters 100, 022113 (2012)
1.6 S.M.Thomas, M.J.Prest, T.E.Whall, D.R.Leadley, E.H.C.Parker, F. Conzattib , N. Serra, D. Esseni, M. De Michielis, A. Paussa, P. Palestri, L. Selmi, L. Donetti, F. Gámiz, R.J.P. Lander, G. Vellianitis, P.-E. Hellström, G. Malm, M. Östling
On the role of Coulomb scattering in hafnium-silicate gated silicon n and p-channel metal-oxide-semiconductor-field-effect-transistors
Journal of Applied Physics 110, 124503 (2011)
1.7 Van Huy Nguyen, A. Dobbie, M. Myronov, D. Norris, T. Walther, D.R. Leadley
Epitaxial Growth by RP-CVD of Relaxed Germanium Layers on (110) and (111) Silicon Substrates
Thin Solid Films 520, 3222–3226 (2012)
1.8 V.A. Shah, A. Dobbie, M. Myronov, D.R. Leadley
Reverse Graded Strain Relaxed SiGe Buffers for CMOS and Optoelectronic Integration
Thin Solid Films 520, 3227–3231 (2012)
1.9 E. Simoen, J. Mitard, B. De Jaeger, G. Eneman, A. Dobbie, M. Myronov, D.R. Leadley, M. Meuris, T. Hoffmann and C. Claeys
Low-frequency noise in strained and relaxed Ge pMOSFETs
IEEE Transactions on Electronic Devices 58, 3132-3139 (2011)
1.10 A. Zhylik, A. Benediktovich, A. Ulyanenkov, H. Guerault, M. Myronov, A. Dobbie, D.R. Leadley, T. .Ulyanenkova
High-resolution X-ray diffraction investigation of relaxation and dislocations in SiGe epilayers grown on (001), (011) and (111) Si substrates
Journal of Applied Physics 109, 123714 (2011)
1.11 A. Zhylik, F. Rinaldi, M. Myronov, K. Saito, S. Menzel, A. Dobbie, D.R. Leadley, T. .Ulyanenkova, I.D. Feranchuk and A. Ulyanenkov
High-resolution reciprocal space mapping of distributed Bragg reflectors and virtual substrates
Physica Status Solidi A, 208, 2582-2586 (2011)
1.12 DJ Norris, IM Ross, A Dobbie, M Myronov, EHC Parker, TE Whall, DR Leadley, T Walther,
A Cross-SectionalTransmission Electron Microscope Analysis of Thin Germanium Layers Grown on Differently Oriented Silicon Wafers
Journal of Crystal Growth (submitted 2011)
1.13 J. Mitard, B. De Jaeger, E. Eneman, A. Dobbie, M. Myronov, M. Kobayashi, J. Geypen, H. Bender, B. Vincent, R. Krom, J. Franco, G. Winderickx, E. Vrancken, W. E. Wang, J. Tseng, R. Loo, K. De Meyer, M. Caymax, L. Pantisano, D.R. Leadley, M. Meuris, P. Absil, S. Biesemans, T. Hoffmann
High hole mobility in 65nm strained Ge-pFETs with HfO2 gate dielectric
Japanese Journal of Applied Physics 50, 04DC17 (2011); 5pp
1.14 V.A. Shah, A. Dobbie, M. Myronov, D.R. Leadley
Effect of Ge/Si (001) epilayer thickness on structural quality
Thin Solid Films 519, 7911–7917 (2011)
1.15 V.A. Shah, A. Dobbie, M. Myronov, D.R. Leadley
High quality relaxed Ge layers grown directly on a Si (001) substrate.
Solid State Electronics 62, 189-194 (2011)
1.16 E. Simoen, J. Mitard, B. De Jaeger, G. Eneman, A. Dobbie, M. Myronov, D.R. Leadley, M. Meuris, T. Hoffmann and C. Claeys
Defect-related excess low-frequency noise in Ge-on-Si pMOSFETs
IEEE Electron Device Letter 32, 87-89 (2011).
1.17 M. Myronov A. Dobbie, V.A. Shah, Xue-Chao Liu, Van H. Nguyen and D. R. Leadley
High quality strained Ge epilayers on a Si0.2Ge0.8/Ge/Si(100) global strain-tuning platform grown by reduced pressure chemical vapour deposition
Electrochemical and Solid-State Letters 13, H388-H390 (2010)
1.18 D.J. Norris, I M Ross, A G Cullis, T Walther, M Myronov, A Dobbie, T Whall, E H C Parker, D R Leadley, B De Jaeger, W Lee and M Meuris
TEM analysis of Si-passivated Ge-on-Si MOSFET structures for high performance PMOS device technology
Electron Microscopy and Analysis Group Conference 2009 (EMAG 2009)
Journal of Physics: Conference Series 241, 012044 (2010), 4pp
1.19 A. Dobbie, M. Myronov, Xue-Chao Liu, Van H. Nguyen, E. H. C. Parker and D. R. Leadley
Investigation of the Thermal Stability of Strained Ge Layers by Reduced-Pressure Chemical Vapour Deposition on Relaxed Si0.2Ge0.8 Buffers
Mater. Res. Soc. Symp. Proc., 1252, I04-06, Mater. Res. Soc. Spring Meeting, San Francisco, U.S.A. (2010)
1.20 A. Dobbie, M. Myronov, Xue-Chao Liu, Van H. Nguyen, E.H.C. Parker and D.R. Leadley
Effect of Growth Rate on the Threading Dislocation Density in Relaxed SiGe Buffers Grown by Reduced Pressure Chemical Vapor Deposition at High Temperature
Semiconductor Science and Technology 25, 085007 (2010)
1.21 D.R. Leadley, D. Dobbie, V.A. Shah and J. Parsons
Introduction to Novel Materials for Nanoscale CMOS in Innovative Materials, Modelling and Characterization for Nanoscale CMOS, Ed. F. Balestra, (Wiley 2010) Chapter 1, p3-22
1.22 D.R. Leadley, D. Dobbie, M. Myronov, V.A. Shah and E.H.C. Parker
Strained Si and Ge Channels in Innovative Materials, Modelling and Characterization for Nanoscale CMOS, Ed. F. Balestra, (Wiley 2010) Chapter 3, p69-126
1.23 V.A. Shah, A. Dobbie, M. Myronov, D.R. Leadley
Reverse graded SiGe/Ge/Si buffers for high composition virtual substrates
Journal of Applied Physics 107, 064304 (2010)
1.24 O.A. Mironov, M. Goiran, J. Galibert, D.V. Kozlov, A.V. Ikonnikov, K.E. Spirin, V.I. Gavrilenko, G. Isella,
M. Kummer, H. von Känel, O. Drachenko, M. Helm, J.Wosnitza, R.J.H. Morris and D.R. Leadley
Cyclotron resonance of extremely conductive 2D holes in high Ge content strained heterostructures
Journal of Low Temperature Physics, 159, 216-221 (2010)
1.25 DJ Norris, T Walther, AG Cullis, M Myronov, A Dobbie, T Whall, EHC Parker, DR Leadley, B De Jaeger, W Lee, M Meuris, J Watling and A Asenov
TEM analysis of Ge-on-Si MOSFET structures with HfO2 dielectric for high performance PMOS device technology
Microscopy of Semiconducting Materials (2009) [Journal of Physics: Conference Series 209, 012061 (2010)]
2 CONFERENCE CONTRIBUTIONS
2.1 A.H.A. Hassan , A. Dobbie, M. Myronov, R. Morris, M. Prest, J. Richardson-Bullock , V. Shah, T. E. Whall, E.H.C. Parker, D.R. Leadley.
Hole Transport Properties in Modulation Doped Germanium Heterostructure
Condensed Matter and Materials Physics, CMMP Edinburgh, 3-7 Sept. (2012)
2.2 D.J. Norris, A. Dobbie, M. Myronov, D.R. Leadley, E.H.C. Parker and T. Walther
Surface roughening of chemical vapour deposited SiGe layers
European Microscopy Congress, Manchester, September 2012
2.3 K. Gallacher, P. Velha, D. Paul, I. Maclaren, M. Myronov, and D. Leadley
Low Specific Ohmic Contacts to n-type Germanium Using a Low Temperature NiGe Process
Pacific Rim Meeting on Electrochemical and Solid State Science (PRiME 2012), Hawaii, October 7-12, (2012)
2.4 J. Halpin, M. Myronov, and D.R. Leadley
Epitaxial growth of highly strained SiGe layers directly on Si
International SiGe Technology and Device Meeting (ISTDM 2012), Berkeley, June 4-6, (2012)
2.5 A. Dobbie, M. Myronov, R.J.H. Morris, M.J. Prest, A.H.A. Hassan, J. Richardson-Bullock, V.A. Shah, E.H.C. Parker, T.E. Whall and D.R. Leadley
Ultra-High Hall Mobility (1 x 106 cm2V-1s-1) in a Two-Dimensional Hole Gas in a Strained Germanium Quantum Well Grown by Reduced Pressure CVD
International SiGe Technology and Device Meeting (ISTDM 2012), Berkeley, June 4-6, (2012)
2.6 Van Huy Nguyen, A. Dobbie, M. Myronov and D.R. Leadley
Understanding the Role of the Low Temperature Seed Layer in the Growth of Low Defect Relaxed Germanium Layers on (111) Silicon by Reduced Pressure CVD
International SiGe Technology and Device Meeting (ISTDM 2012), Berkeley, June 4-6, (2012)
2.7 M. Myronov, Xue-Chao Liu, A. Dobbie and D.R. Leadley
Precise thickness and strain control during epitaxial growth of strained Ge/SiGe multilayers by industrial class CVD International Conference on Solid State Devices and Materials (SSDM) Nagoya, Japan Sept. 28-30, (2011)
2.8 Van Huy Nguyen, A. Dobbie, M. Myronov, D. Norris, T. Walther, D.R. Leadley
Epitaxial Growth by RP-CVD of Relaxed Germanium Layers on (110) and (111) Silicon Substrates
7th International Conference on Si Epitaxy and Heterostructures (ICSI-7), Leuven, Belgium, Sept. (2011)
2.9 V.A. Shah, A. Dobbie, M. Myronov, D.R. Leadley
Reverse Graded Strain Relaxed SiGe Buffers for CMOS and Optoelectronic Integration
7th International Conference on Si Epitaxy and Heterostructures (ICSI-7), Leuven, Belgium, Sept. (2011)
2.10 L. Donetti, F. Gámiz, S.M. Thomas, T.E. Whall, D.R. Leadley, P.E. Hellström, G. Malm, M. Östling
On the effective mass of holes in inversion layers
ULIS 2011, Cork, Ireland, 14-16 March 2011
2.11 Van Huy Nguyen, A. Dobbie, M. Myronov, D. Norris, T. Walther, D.R. Leadley
Microscopy-based studies of defect formation in relaxed Ge grown on (110) and (111) Si substrates by RP-CVD
Microscopy of Semiconducting Materials (MSM XVII), Cambridge, UK 4-7 April (2011)
2.12 D.J. Norris, I.M. Ross, A. Dobbie, M. Myronov, E.H.C. Parker, T.E. Whall, D.R. Leadley, T. Walther
Interface studies of germanium on silicon (111) using aberration corrected scanning transmission electron microscopy
Microscopy of Semiconducting Materials (MSM XVII), Cambridge, UK 4-7 April (2011)
2.13 D. Norris, T. Walther, A. Dobbie, M. Myronov, E.H.C. Parker, T.E. Whall, D.R. Leadley
A cross-sectional transmission electron microscope analysis of SiGe multilayers grown on (001) silicon to investigate the Stranski-Krastanow Transition
Microscopy of Semiconducting Materials (MSM XVII), Cambridge, UK 4-7 April (2011)
2.14 E. Simoen, J. Mitard, B. De Jaeger, G. Eneman, A. Dobbie, M. Myronov, D.R. Leadley, M. Meuris, T. Hoffmann and C. Claeys
Low-frequency noise in strained and relaxed Ge pMOSFETs
10th Int. Conf. on Solid-State and Integrated Circuit Technology (IC-SICT 2010), Shanghai, Nov 1-4, 891-3 (2010)
2.15 J. Mitard, B. De Jaeger, E. Eneman, A. Dobbie, M. Myronov, M. Kobayashi, J. Geypen, H. Bender, B. Vincent, R. Krom, J. Franco, G. Winderickx, E. Vrancken, W. E. Wang, J. Tseng, R. Loo, K. De Meyer, M. Caymax, L. Pantisano, D.R. Leadley, M. Meuris, P. Absil, S. Biesemans, T. Hoffmann
High Hole-Mobility 65nm Biaxially-Strained Ge-pFETs: Fabrication, Analysis and Optimization
2010 Int. Conf. on Solid State Devices and Materials (SSDM 2010), Tokyo, Japan, 22-24 Sept (2010), p. C-9-2.
2.16 I.D. Feranchuk, F.Rinaldi, S. Menzel, M. Myronov, A. Dobbie, D.R. Leadley, A. Zhilik, K. Saito, A. Ulyanenkov
High-Resolution Reciprocal Space Mapping of Multilayers with Concentration and Relaxation Gradients
10th Conf. on High Resolution X-Ray Diffraction and Imaging (XTOP 2010), Warwick, 20-23 Sept. (2010)
2.17 A. Zhilik, M. Myronov, A. Dobbie, D.R. Leadley, H. Guerault, T. Ulyanenkova, A. Benediktovitch, A. Ulyanenkov
Reciprocal Space Mapping of Graded SiGe Buffers Grown on Non-Standard Orientation Si Substrates
10th Conf. on High Resolution X-Ray Diffraction and Imaging (XTOP 2010), Warwick, 20-23 Sept. (2010)
2.18 A. Ulyanenkov, M. Myronov, A. Dobbie, D.R. Leadley, H. Guerault, A. Benediktovitch, A. Zhilik, T. Ulyanenkova, and K. Shcherbachev
High-Resolution X-ray Reciprocal Space Mapping of High Ge Content Graded SiGe Buffers Grown on Non-Standard Orientation Si Substrates
16th International Conference on Crystal Growth (ICCG-16), Beijing, China August 8-13, 2010
2.19 DJ Norris, T Walther, AG Cullis, M Myronov, A Dobbie, T Whall, EHC Parker, DR Leadley, B De Jaeger, W Lee, M Meuris, J Watling and A Asenov
A Transmission Electron Microscopical Analysis of SiGe Grown on a Range of Differently Oriented Si Wafers
UK Semiconductors, Sheffield, July 7-8 (2010)
2.20 Van Huy Nguyen, A. Dobbie, M. Myronov, and D. R. Leadley
Defect Evaluation in Ge and Si1-xGex Epitaxial Layers using an Iodine-Based Selective Etchant
UK Semiconductors, Sheffield, July 7-8 (2010)
2.21 A. Dobbie, M. Myronov, Van Huy Nguyen, Xue-Chao Liu and D. R. Leadley
Thermal Stability of Strained Ge Layers Grown on Reverse-Graded Si0.2Ge0.8 Relaxed Buffers by RP-CVD
UK Semiconductors, Sheffield, July 7-8 (2010)
2.22 V.A. Shah, A. Dobbie, M. Myronov, D.R. Leadley
Thickness studies of high quality Ge layers on Si (001) substrates.
UK Semiconductors, Sheffield, July 7-8 (2010)
2.23 A. Dobbie, M. Myronov, Xue-Chao Liu, Van H. Nguyen, E. H. C. Parker and D. R. Leadley
Relaxation of Strained Germanium Layers Grown on Si0.2Ge0.8 Relaxed Buffers by RP-CVD with in-situ H2 Annealing
E-MRS 2010 Spring Meeting, Strasbourg, France, June 7-11, 2010
2.24 M. Myronov, Xue-Chao Liu and D.R. Leadley
Epitaxial growth of Ge layers by RP-CVD using Digermane precursor
E-MRS 2010 Spring Meeting, Strasbourg, France, June 7-11, 2010
2.25 V.A. Shah, A. Dobbie, M. Myronov, D.R. Leadley
High quality relaxed Ge layers grown directly on a Si (001) substrate.
ISTDM 2010, Stockholm 24-26 May 2010
2.26 A. Dobbie, M. Myronov, Xue-Chao Liu, Van H. Nguyen, E. H. C. Parker and D. R. Leadley
Investigation of the Thermal Stability of Strained Ge Layers by Reduced-Pressure Chemical Vapour Deposition on Relaxed Si0.2Ge0.8 Buffers
MRS Spring Meeting, April 5-9 2010, San Francisco
2.27 V.H. Nguyen, A. Dobbie, M. Myronov, V.A. Shah, X-C. Liu and D.R. Leadley
Characterisation of Strained Ge Epitaxial Layers Grown by RPCVD on Reverse Graded Si0.2Ge0.8 Relaxed Buffers
Institute of Physics Condensed Matter and Materials Physics Conference, Warwick, Dec 17-19 (2009).
2.28 M. Myronov, V.A. Shah, A. Dobbie, Xue-Chao Liu, Van H. Nguyen and D. R. Leadley
“Compressively strained Ge channel heterostructures grown by RP-CVD for the next generation CMOS devices”.
2009 International Conference on Solid State Devices and Materials (SSDM 2009), October 6-9, 2009, Sendai, Japan, (Oral presentation)
2.29 DJ Norris, IM Ross, AG Cullis, T Walther, M Myronov, A Dobbie, T Whall, EHC Parker, DR Leadley, B De Jaeger, W Lee and M Meuris
TEM analysis of Si-passivated Ge-on-Si MOSFET structures for high performance PMOS device technology
Proc. EMAG 2009, Sheffield, UK 8-11 September 2009
2.30 D. R. Leadley, V.A. Shah, A. Dobbie and M. Myronov
“Reverse graded virtual substrates for strained Ge devices”.
UK Semiconductors 2009, July 1-2, 2009, Sheffield, UK, C-O-11 . (Oral presentation)
2.31 O.A. Mironov, M. Goiran, J. Galibert, D.V. Kozlov, A.V. Ikonnikov, K.E. Spirin, V.I. Gavrilenko, G. Isella,
M. Kummer, H. von Känel, O. Drachenko, M. Helm, J.Wosnitza, R.J.H. Morris and D.R. Leadley
Cyclotron resonance of extremely conductive 2D holes in high Ge content strained heterostructures
9th International Conference on Research in High Magnetic Fields (RHMF 09), Dresden, July 22-25 (2009)
2.32 DJ Norris, T Walther, AG Cullis, M Myronov, A Dobbie, T Whall, EHC Parker, DR Leadley, B De Jaeger, W Lee, M Meuris, J Watling and A Asenov
TEM analysis of Ge-on-Si MOSFET structures with HfO2 dielectric for high performance PMOS device technology
Microscopy of Semiconducting Materials (2009) [Journal of Physics: Conference Series]
2.33 M. Myronov and D.R. Leadley
Realization of globally strained Ge layers
E-MRS Strasbourg, France, June 8-12, (2009) Invited talk
2.34 M. Myronov, A. Dobbie, V.A. Shah and D.R. Leadley
Epitaxial growth of compressive strained Ge layers on reverse linearly graded virtual substrate by RP-CVD
E-MRS 2009, Strasbourg, France, June 8-12, (2009)
2.35 A. Dobbie, M. Myronov, X. Liu, E. H. C. Parker and D. R. Leadley
Effect of Si1-xGex Growth Rate on the Threading Dislocation Density in Fully Relaxed Si1-xGex/Si(100) Virtual Substrates Grown at High Temperature by RP-CVD
E-MRS 2009, Strasbourg, France, June 8-12, (2009)
2.36 M. Myronov, A. Dobbie, V.A. Shah and D.R. Leadley
Low temperature epitaxial growth of compressive strained Ge layers on reverse linearly graded virtual substrate by RP-CVD
ICSI-6: 6th Int. Conf. Silicon Epitaxy and Heterostructures, Los Angeles, California, USA, May 17 – 22, (2009)