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Advances in SiGeSn technology

Published online by Cambridge University Press:  26 July 2012

Richard Soref ,
John Kouvetakis ,
John Tolle ,
Jose Menendez  and
Vijay D’Costa
Richard Soref*
Affiliation:
Sensors Directorate, Air Force Research Laboratory, Hanscom Air Force Base, Massachusetts 01731
John Kouvetakis
Affiliation:
Department of Chemistry and Biochemistry, Arizona Sate University, Tempe, Arizona 85287
John Tolle
Affiliation:
Department of Chemistry and Biochemistry, Arizona Sate University, Tempe, Arizona 85287
Jose Menendez
Affiliation:
Department of Physics and Astronomy, Arizona Sate University, Tempe, Arizona 85287
Vijay D’Costa
Affiliation:
Department of Physics and Astronomy, Arizona Sate University, Tempe, Arizona 85287
*
a) Address all correspondence to this author. e-mail: [email protected]
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Abstract

We recently reported the chemical vapor deposition growth of binary Ge1–ySny and ternary Ge1–ySixSny alloys directly on Si wafers using SnD4, Ge2H6 (di-germane), SiH3GeH3, and (GeH3)2SiH2 sources. Ge1–ySny is an intriguing infrared (IR) material that undergoes an indirect-to-direct band-gap transition for y < 0.1. In addition, we have found that Ge1–ySny layers have ideal properties as templates for the subsequent deposition of other semiconductors: (i) they are strain-relaxed and have low threading-defect densities (105 cm−2) even for films thinner than 1 μm; (ii) their low growth temperatures between 250 and 350 °C are compatible with selective growth, and the films possess the necessary thermal stability for conventional semiconductor processing (up to 750 °C, depending on composition); (iii) they exhibit tunable lattice constants between 5.65 Å and at least 5.8 Å, matching InGaAs and related III-V systems; (iv) their surfaces are extremely flat; (v) they grow selectively on Si and not on SiO2; and (vi) the film surface can be prepared by simple chemical cleaning for subsequent ex situ epitaxy. The incorporation of Sn lowers the absorption edges of Ge. Therefore, Ge1–ySny is attractive for detector and photovoltaic applications that require band gaps lower than that of Ge. Spectroscopic ellipsometry and photoreflectance experiments show that the direct band gap is halved for as little as y = 0.15. Studies of a Ge0.98Sn0.02 sample yield an absorption coefficient of 3500 cm−1 at 1675 nm (0.74 eV). Thus, IR detectors based on Ge0.98Sn0.02 could easily cover the L-(1565–1625 nm) and C-(1530–1565 nm) telecomm bands. Photoluminescence studies show band-gap emission on thin GeSn layers sandwiched between higher band-gap SiGeSn barriers. We have made advances in p- and n-doping of GeSn and present results on electrical characterizations. Hall measurements reveal mobilities as high as of 600 cm2/V-s and background p-dopant concentrations in the 1016 cm−3 range for samples with nominal composition and thickness of Ge0.98Sn0.02 and ∼500 nm, respectively. GeSn also has application in band-to-band laser heterodiodes. The ternary system Ge1–x–ySixSny grows on Ge1–ySny-buffered Si. It represents the first practical group IV ternary alloy, because C can only be incorporated in minute amounts to the Ge–Si network. The most significant feature of Ge1–x–ySixSny is the possibility of independent adjustment of the lattice constant and band gap. For the same value of the lattice constant, one can obtain band gaps differing by >0.2 eV, even if the Sn concentration is limited to the range y < 0.2. This property can be used to develop a variety of novel devices, from multicolor detectors to multiple-junction photovoltaic cells. A linear interpolation of band-gap lattice constants between Si, Ge, and α–Sn shows that it is possible to obtain SiGeSn with a band gap and a lattice constant larger than that of Ge. We shall use this feature to make a tensile-strained Ge-on-SiGeSn telecomm detector with improved performance. To date, record high tensile strain (0.40%) has been achieved in Ge layers grown on GeSn-buffered Si where the strain is systematically tuned by adjusting the lattice constant in the buffer. A tensile-strain-induced direct gap of Ge can be used also for laser diodes and electroptical modulators.

Keywords

Chemical vapor deposition (CVD) (deposition)LaserOptoelectronics
Type
Outstanding Meeting Papers
Information
Journal of Materials Research , Volume 22 , Issue 12 , December 2007 , pp. 3281 - 3291
Copyright
Copyright © Materials Research Society 2007

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References

REFERENCES

1Bauer, M.R., Taraci, J., Tolle, J., Chizmeshya, A.V.G., Zollner, S., Menendez, J., Smith, D.J.Kouvetakis, J.: Ge-Sn semiconductors for band gap and lattice engineering. Appl. Phys. Lett. 81, 2992 2002Google Scholar
2Kouvetakis, J., Menendez, J.Chizmeshya, A.V.G.: Tin-based group IV semiconductors: New platforms for opto- and microelectronics on silicon. Annu. Rev. Mater. Res. 36, 497 2006Google Scholar
3Roucka, R., Tolle, J., Cook, C., Costa, V.J., Chizmeshya, A.V.G., Menendez, J., Zollner, S.Kouvetakis, J.: Versatile buffer layer architectures based on Ge1–xSnx alloys. Appl. Phys. Lett. 86, 191912 2005CrossRefGoogle Scholar
4Bauer, M.R., Kouvetakis, J., Smith, D.J.Menendez, J.: Tunable band structure in diamond-cubic tin-germanium alloys grown on silicon substrates. Solid State Commun. 127, 355 2003Google Scholar
5D’Costa, V., Cook, C., Birdwell, A.G., Littler, C.A., Zollne, S., Kouvetakis, J.Menendez, J.: Optical critical points of thin-film Ge1–ySny alloys: A comparative Ge1–ySny/Ge1–xSix study. Phys. Rev. B: Solid State 73, 125207 2006Google Scholar
6Chizmeshya, A.V.G., Ritter, C., Tolle, J., Cook, C., Menendez, J.Kouvetakis, J.: Fundamental studies of P(GeH3)3, As(GeH3)3, and Sb(GeH3)3: Practical n-dopants for new group IV semiconductors. Chem. Mater. 18, 6266 2006Google Scholar
7Aella, P., Cook, C., Tolle, J., Zollner, S., Chizmeshya, A.V.G.Kouvetakis, J.: Optical and structural properties of SixSnyGe1–x–y alloys. Appl. Phys. Lett. 84, 888 2004Google Scholar
8Tolle, J., Roucka, R., D’Costa, V., Menendez, J., Chizmeshya, A.Kouvetakis, J.: Compliant tin-based buffers for the growth of defect-free strained heterostructures on silicon. Appl. Phys. Lett. 88(25), 252112 2006Google Scholar
9Menendez, J., D’Costa, V.R., Cook, S.C., Menéndez, J., Tolle, J., Kouvetakis, J.Zollner, S.: Transferability of optical bowing parameters between binary and ternary group-IV alloys. Solid State Commun. 138(6), 309 2006Google Scholar
10Ishikawa, Y., Wada, K., Cannon, D.D., Liu, J., Luan, H-C.Kimerling, L.C.: Strain-induced band gap shrinkage in Ge grown on Si substrates. Appl. Phys. Lett. 82, 2044 2003CrossRefGoogle Scholar
11Menendez, J.Kouvetakis, J.: Type-I Ge/Ge1–x–ySixSny strained-layer heterostructures with a direct Ge bandgap. Appl. Phys. Lett. 85(7), 1175 2004CrossRefGoogle Scholar
12Fang, Y-Y., Tolle, J., D’Costa, V., Menendez, J.Kouvetakis, J.: Perfectly tetragonal tensile-strained Ge on Ge1–ySny buffered Si(100). Appl. Phys. Lett. 90, 061915 2007Google Scholar
13Soref, R.A.Friedman, L.: Direct gap Ge/GeSn/Si heterostructures. Superlattices Microstruct. 14(213), 189 1993Google Scholar
14Soref, R.A., Kouvetakis, J.Menendez, J.: Strain-engineered direct-gap Ge/SnxGe1−x heterodiode and multi-quantum-well photodetectors, laser, emitters and modulators grown on SnySizGe1–y–z-buffered silicon, U.S. Patent No. 6 897 471 (2005),Google Scholar
15Tolle, J., D’Costa, V., Chizmeshya, A.V.G., Hu, C-W., Tsong, I.S.T., Menendez, J.Kouvetakis, J.: Low temperature chemical vapor deposition of Si-based compounds via SiH3SiH2SiH3: Metastable SiSn/GeSn/Si(100) heteroepitaxial structures. Appl. Phys. Lett. 89, 231924 2006Google Scholar
16Roucka, R., Tolle, J., D’Costa, V., Menendez, J.Kouvetakis, J.: Ge1−ySny/Si(100) composite substrates for growth of InxGa1−xAs and GaAs1−xSbx alloys. J. Appl. Phys. 101, 013518 2007Google Scholar