Technology development for III-V tunnel FETs on a silicon platform
Partners: IBM, EPFL
- InAs-Si heterojunction nanowire (NW) TFETs were successfully demonstrated and analysed, with good overall performance in terms of trade-off between high Ion versus small slope and high Ion/Ioff ratio, cf. D2.4, M2.5. (Ion ≈ 2.4 μA/μm, Ion/Ioff ≈ 106, slope of 150 mV/dec over three decades) [1,2]
- InAs-Si heterojunction NW tunnel diodes with excellent performance were achieved highlighting the benefits of the InAs-Si heterostructure for TFETs. Very high tunnel currents of 6 MA/cm2 at 0.5 V reverse bias and negative differential resistance in forward bias with high peak current density of up to 570 kA/cm2 was demonstrated. [3,4]
- In-situ doping of InAs NWs up to a concentration of 7∙1019 cm-3 has been successfully established 
- Seebeck measurements have been applied to derive the charge carrier density and together with NW resistance measurements the mobility. [5, 6]
- Ni-alloyed InAs contacts with low contact resistance were demonstrated. 
- Tunnel spectroscopy was applied to investigate the InAs-Si tunnel junction. 
- A new growth approach based on selective epitaxy in nanotube templates was successfully developed to integrate III-V materials on a Si platform for TFETs. [8, 9]
- Scaled diameters of 25 nm and high yield in nanowire growth and functioning TFET devices was achieved. 
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Fig. 1: Schematic of InAs-Si (a) tunnel diode and (b) TFET. (c) SEM image showing a heterojunction NW. The InAs NW is grown on Si <111> by selective area growth .
Fig. 1 (d): HR-TEM image of the InAs-Si interface. (e) FIB cut of InAs-Si TFET. [1, 4]
Fig. 2: Resistivity versus doping concentration of InAs NWs. 
Fig. 3: InAs-Si Esaki diodes. Influence of the n-doping level in InAs. 
Fig. 4: InAs-Si nanowire TFET (A) Temperature dependence of Ion at VG=-1V. (B) TFET Ion vs VG before and after Ni-alloying. 
Fig. 5: Integration of III-V materials on Si. Epitaxial growth of InAs NWs and InAs-InSb NW heterojunctions within a template. (a) InAs NW within template. (b) Selective growth of InSb on InAs. The SEM image on the right of the array shows a NW with the template removed. (c) InSb growth extending out of the template. Scale bar is 100 nm. 
- K. E. Moselund, H. Schmid, C. Bessire, M. T. Björk, H. Ghoneim, H. Riel "InAs–Si Nanowire Heterojunction Tunnel FETs", IEEE Electron Device Letters, Vol. 33 (10), 1453–1455, 2012.
- H. Schmid, K. E. Moselund, M. T. Björk, M. Richter, H. Ghoneim, C. D. Bessire and H. Riel, "Fabrication of Vertical InAs-Si Heterojunction Tunnel Field Effect Transistors", IEEE 69th Device Research Conference Digest, 181–182, 2011.
- IM. T. Björk, H. Schmid, C. D. Bessire, K. E. Moselund, H. Ghoneim, E. Lörtscher, S. Karg, H. Riel "Si–InAs heterojunction Esaki tunnel diodes with high current densities", Appl. Phys. Lett. 97, 163501, 2010.
- H. Riel, K. E. Moselund, C. Bessire, M. T. Björk, A. Schenk, H. Ghoneim, H. Schmid, "InAs-Si Heterojunction Nanowire Tunnel Diodes and Tunnel FETs", Proc. of IEEE IEDM 2012.
- H. Ghoneim, P. Mensch, H. Schmid, C. Bessire, R.Rhyner, A. Schenk, C. Rettner, S. Karg, K. E. Moselund, H. Riel, M. Björk "In situ doping of catalyst-free InAs nanowires", Nanotechnology 23 505708, 2012.
- S. Karg, P. Mensch, H. Schmid, P. Das Kanungo, H. Ghoneim, V. Schmidt, M. Björk, V. Troncale, H. Riel, "Measurement of Thermoelectric Properties of Single Semiconductor Nanowires", Journal of Electronic Materials, Vol. 42(7), p. 2409-2414, 2013.
- C. D. Bessire, M. T. Björk, H. Schmid, A. Schenk, K. B. Reuter, and H. Riel, "Trap-Assisted Tunneling in Si-InAs Nanowire Heterojunction Tunnel Diodes", Nano Letters Vol. 11(10), 4195–9, 2011.
- P. Das Kanungo, H. Schmid, M. T. Björk, L. M. Gignac, C. Breslin, J. Bruley, C. D. Bessire and H. Riel, "Selective Area Growth of III-V Nanowires on Silicon in a Nanotube Template: Towards Monolithic Integration of Nano-Devices", Nanotechnology, Vol. 24(22), p. 225304, 2013.
- M. Borg, H. Schmid, K. E. Moselund, G. Signorello, L. Gignac, J. Bruley, C. Breslin, P. Das Kanungo, P. Werner, H. Riel, submitted.
- M. T. Björk, H. Schmid, C. Breslin, L. Gignac, H. Riel "InAs Nanowire Growth on <111> Silicon", J. Cryst. Growth, Vol. 344, Issue 1, 31–37, 20124] H. Riel, K. E. Moselund, C. Bessire, M. T. Björk, A. Schenk, H. Ghoneim, H. Schmid, "InAs-Si Heterojunction Nanowire Tunnel Diodes and Tunnel FETs", Proc. of IEEE IEDM 2012.