Band engineering and growth of tensile strained Ge/(Si)GeSn heterostructures for tunnel field effect transistors

Wirths, Stephan; Tiedemann, A. T.; Ikonić, Z.; Harrison, P.; Holländer, B.; Stoïca, T.; Mußler, Gregor; Myronov, Maksym; Hartmann, Jean‐Michel; Grützmacher, Detlev; Buca, D.; Mantl, S.

doi:10.1063/1.4805034

Cited by 146 publications

(113 citation statements)

References 21 publications

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“…The GeSn epilayers are grown on Gebuffered (thickness 2.5 µm) Si(001) substrates (Ge-VS) 24 using a reactive gas source epitaxy process adapted to an industrial reduced pressure chemical vapor deposition (RP-CVD) reactor with showerhead technology, process temperatures in the 350°C to 375°C range, and Ge2H6 and SnCl4 as precursor gases. 25,26 In contrast to the approach of Chen et al 23 where pseudomorphic and, thus, highly compressively strained and indirect GeSn/Ge quantum well structures were used, the active layers of the laser cavities presented here are grown with thicknesses far beyond the critical thickness for strain relaxation. This -as we showed previously 19,20 -allows to cross the indirect-to-direct bandgap transition while maintaining a high crystalline quality.…”

Section: Resultsmentioning

confidence: 99%

Optically Pumped GeSn Microdisk Lasers on Si

et al. 2016

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The strong correlation between advancing the performance of Si microelectronics and their demand of low power consumption requires new ways of data communication. Photonic circuits on Si are already highly developed except for an eligible on-chip laser source integrated monolithically. The recent demonstration of an optically pumped waveguide laser made from the Si-congruent GeSn alloy, monolithical laser integration has taken a big step forward on the way to an all-inclusive nanophotonic platform in CMOS. We present group IV microdisk lasers with significant improvements in lasing temperature and lasing threshold compared to the previously reported nonundercut Fabry−Perot type lasers. Lasing is observed up to 130 K with optical excitation density threshold of 220 kW/cm 2 at 50 K. Additionally the influence of strain relaxation on the band structure of undercut resonators is discussed and allows the proof of laser emission for a just direct Ge 0.915 Sn 0.085 alloy where Γ and L valleys have the same energies. Moreover, the observed cavity modes are identified and modeled.

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Section: Resultsmentioning

confidence: 99%

Optically Pumped GeSn Microdisk Lasers on Si

et al. 2016

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“…Low bandgap semiconductors with a direct gap are particularly desired for novel low power devices such as tunnel-field effect transistors (Tunnel-FET). 7,8 In this context, the electronic band structure of Ge can be tuned by applying biaxial tensile strain 9 or by Sn alloying 10 towards a fundamental direct bandgap which enhances the tunneling probability and thus the ON-current of Tunnel-FETs 8,11,12 . Vertical Tunnel-FET structures using strained Ge channels were recently proposed based on InGaAs 13 and GeSn 11 buffer substrates.…”

mentioning

confidence: 99%

High-k Gate Stacks on Low Bandgap Tensile Strained Ge and GeSn Alloys for Field-Effect Transistors

Wirths

Stange

Pampillón

et al. 2014

ACS Appl. Mater. Interfaces

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We present the epitaxial growth of Ge and Ge 0.94 Sn 0.06 layers with 1.4% and 0.4% tensile strain, respectively, by reduced pressure chemical vapor deposition on relaxed GeSn buffers and the formation of high-k/metal gate stacks thereon. Annealing experiments reveal that process temperatures are limited to 350 °C to avoid Sn diffusion. Particular emphasis is placed on the electrical characterization of various high-k dielectrics, as 5 nm Al 2 O 3 , 5 nm HfO 2 , or 1 nmAl 2 O 3 /4 nm HfO 2 , on strained Ge and strained Ge 0.94 Sn 0.06 . Experimental capacitance− voltage characteristics are presented and the effect of the small bandgap, like strong response of minority carriers at applied field, are discussed via simulations.

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“…Another advantage of GeSn is the use as stressor or as strained material, resulting from the lattice mismatch with Ge or Si. It is therefore a good candidate as compressive source and drain stressor in p-type Ge-channel metal oxide semiconductor field effect transistors (pMOSFETs) [4][5][6][7] or as channel material [8,9] within a postscaling approach [10]. Being a group-IV material is also an asset for the integration into current Si-based technologies, although the successful incorporation of other alloys such as III-V compounds on Si has already been demonstrated [11][12][13][14].…”

Section: Introductionmentioning

confidence: 99%

Electrical characterization of p-GeSn/n-Ge diodes with interface traps under dc and ac regimes

Baert

Gupta

Gencarelli

et al. 2015

Solid-State Electronics

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In this work, the electrical properties of p-GeSn/n-Ge diodes are investigated in order to assess the impact of defects at the interface between Ge and GeSn using temperature-dependent current-voltage and capacitance-voltage measurements. These structures are made from GeSn epitaxial layers grown by CVD on Ge with in-situ doping by Boron. As results, an average ideality factor of 1.2 has been determined and an activation energy comprised between 0.28 eV and 0.30 eV has been extracted from the temperature dependence of the reverse-bias current. Based on the comparison with numerical results obtained from device simulations, we explain this activation energy by the presence of traps located near the GeSn/Ge interface.

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Band engineering and growth of tensile strained Ge/(Si)GeSn heterostructures for tunnel field effect transistors

Cited by 146 publications

References 21 publications

Optically Pumped GeSn Microdisk Lasers on Si

Optically Pumped GeSn Microdisk Lasers on Si

High-k Gate Stacks on Low Bandgap Tensile Strained Ge and GeSn Alloys for Field-Effect Transistors

Electrical characterization of p-GeSn/n-Ge diodes with interface traps under dc and ac regimes

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