Source/Drain Materials for Ge nMOS Devices: Phosphorus Activation in Epitaxial Si, Ge, Ge1-xSnx and SiyGe1-x-ySnx
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A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
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en
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13
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ECS Journal of Solid State Science and Technology, Volume 9, issue 4, pp. 1-13
Abstract
This paper benchmarks various epitaxial growth schemes based on n-type group-IV materials as viable source/drain candidates for Ge nMOS devices. Si:P grown at low temperature on Ge, gives an active carrier concentration as high as 3.5 × 1020 cm−3 and a contact resistivity down to 7.5 × 10−9 Ω.cm2. However, Si:P growth is highly defective due to large lattice mismatch between Si and Ge. Within the material stacks assessed, one option for Ge nMOS source/drain stressors would be to stack Si:P, deposited at contact level, on top of a selectively grown n-Si y Ge1−x−y Sn x at source/drain level, in line with the concept of Si passivation of n-Ge surfaces to achieve low contact resistivities as reported in literature (Martens et al. 2011 Appl. Phys. Lett., 98, 013 504). The saturation in active carrier concentration with increasing P (or As)-doping is the major bottleneck in achieving low contact resistivities for as-grown Ge or Si y Ge1−x−y Sn x . We focus on understanding various dopant deactivation mechanisms in P-doped Ge and Ge1−x Sn x alloys. First principles simulation results suggest that P deactivation in Ge and Ge1−x Sn x can be explained both by P-clustering and donor-vacancy complexes. Positron annihilation spectroscopy analysis, suggests that dopant deactivation in P-doped Ge and Ge1−x Sn x is primarily due to the formation of P n -V and Sn m P n -V clusters.Description
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Vohra, A, Makkonen, I, Pourtois, G, Slotte, J, Porret, C, Rosseel, E, Khanam, A, Tirrito, M, Douhard, B, Loo, R & Vandervorst, W 2020, 'Source/Drain Materials for Ge nMOS Devices: Phosphorus Activation in Epitaxial Si, Ge, Ge1-xSnx and SiyGe1-x-ySnx', ECS Journal of Solid State Science and Technology, vol. 9, no. 4, 044010, pp. 1-13. https://doi.org/10.1149/2162-8777/ab8d91