Germanium-tin

Germanium-tin is an alloy of the elements germanium and tin, both located in group 14 of the periodic table. It is only thermodynamically stable under a small composition range. Despite this limitation, it has useful properties for band gap and strain engineering of silicon-integrated optoelectronic and microelectronic semiconductor devices.

Synthesis

Germanium-tin alloys must be kinetically stabilized in order to prevent decomposition.[1][2] Therefore, low temperature molecular beam epitaxy or chemical vapor deposition techniques are typically used for their synthesis.[1]

Microelectronic applications

Germanium-tin alloys have higher carrier mobilities than either silicon or germanium. Therefore, it has been proposed that they can be used as a channel material in high speed metal-oxide-semiconductor field effect transistors.[3] In addition, the alloys' larger lattice constant relative to germanium makes it possible to use them as stressors to enhance the carrier mobility of germanium channel transistors.[3][4]

Optoelectronic applications

At a Sn content beyond approximately 9%, germanium-tin alloys become direct gap semiconductors having efficient light emission suitable for the fabrication of lasers.[5] Since the constituent elements are chemically compatible with silicon, it is possible to integrate such lasers directly onto silicon microelectronic devices, enabling on-chip optical communication. This is still an active research area, but germanium-tin lasers operating at low temperatures have already been demonstrated.[6][7] In addition, germanium-tin light emitting diodes operating at room temperature have also been reported.[8][9]

References

  1. ^ a b Wirths, S.; Buca, D.; Mantl, S. (2016). "Si–Ge–Sn alloys: From growth to applications". Progress in Crystal Growth and Characterization of Materials. 62 (1). Elsevier BV: 1–39. doi:10.1016/j.pcrysgrow.2015.11.001. ISSN 0960-8974.
  2. ^ Kouvetakis, J.; Menendez, J.; Chizmeshya, A.V.G. (2006). "Tin-Based Group IV Semiconductors: New Platforms for Opto- and Microelectronics on Silicon". Annual Review of Materials Research. 36 (1). Annual Reviews: 497–554. Bibcode:2006AnRMS..36..497K. doi:10.1146/annurev.matsci.36.090804.095159. ISSN 1531-7331.
  3. ^ a b Loo, R.; Vincent, B.; Gencarelli, F.; Merckling, C.; Kumar, A.; et al. (2012-12-07). "Ge1−xSnx Materials: Challenges and Applications". ECS Journal of Solid State Science and Technology. 2 (1). The Electrochemical Society: N35 – N40. doi:10.1149/2.039301jss. ISSN 2162-8769.
  4. ^ Vincent, B.; Shimura, Y.; Takeuchi, S.; Nishimura, T.; Eneman, G.; et al. (2011). "Characterization of GeSn materials for future Ge pMOSFETs source/drain stressors". Microelectronic Engineering. 88 (4). Elsevier BV: 342–346. doi:10.1016/j.mee.2010.10.025. ISSN 0167-9317.
  5. ^ Gallagher, J. D.; Senaratne, C. L.; Kouvetakis, J.; Menéndez, J. (2014-10-06). "Compositional dependence of the bowing parameter for the direct and indirect band gaps in Ge1−ySny alloys". Applied Physics Letters. 105 (14). AIP Publishing: 142102. doi:10.1063/1.4897272. hdl:2286/R.I.27074. ISSN 0003-6951.
  6. ^ "Scientists construct the first germanium-tin semiconductor laser for silicon chips". Phys.org. 2015-01-20. Retrieved 2019-12-12.
  7. ^ Prachi Patel (2015-01-22). "The Germanium-Tin Laser: Answer to the On-Chip Data Bottleneck?". IEEE Spectrum. Retrieved 2019-12-12.
  8. ^ Gallagher, J. D.; Senaratne, C. L.; Sims, P.; Aoki, T.; Menéndez, J.; Kouvetakis, J. (2015-03-02). "Electroluminescence from GeSn heterostructure pin diodes at the indirect to direct transition". Applied Physics Letters. 106 (9). AIP Publishing: 091103. Bibcode:2015ApPhL.106i1103G. doi:10.1063/1.4913688. hdl:2286/R.I.29217. ISSN 0003-6951.
  9. ^ Senaratne, C. L.; Wallace, P. M.; Gallagher, J. D.; Sims, P. E.; Kouvetakis, J.; Menéndez, J. (2016-07-14). "Direct gap Ge1−ySny alloys: Fabrication and design of mid-IR photodiodes". Journal of Applied Physics. 120 (2). AIP Publishing: 025701. doi:10.1063/1.4956439. hdl:2286/R.I.45246. ISSN 0021-8979.