张应变锗薄膜制备技术的研究进展
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摘要
由于与硅集成电路工艺兼容的张应变锗薄膜在光电器件如光电探测器、调制器,特别是发光器件中具有潜在的应用前景,使其得到了广泛关注。然而,在锗薄膜中引入可控的、大的张应变是个挑战。综述了张应变锗薄膜制备技术的研究进展,重点介绍了在锗薄膜中引入张应变的外延技术、应变转移技术、应变浓缩技术和机械应变技术的工艺流程和实验结果,并讨论了它们的优点和缺点。采用应变浓缩技术制备的厚度为350 nm的锗薄膜微桥的单轴张应变和微盘的双轴张应变分别达到了4.9%和1.9%,可将锗调制为直接带隙材料,适用于锗激光器的研制。
Tensile strained Ge thin films which are compatible with Si integrated circuits technology have attracted great attention due to their potential applications in optoelectric devices such as photodetector,modulator,and especially light emitting devices. However, introducing a controllable and large tensile strain to Ge thin films is a challenge. The research progresses of fabrication techniques of tensilely strained Ge thin films are reviewed. The fabrication process flow and test results of various approaches including epitaxy technology,strain transfer technology,strain concentration technology and mechanical strain technology to apply tensile strain to Ge thin films are introduced,respectively. And the advantages and disadvantages of these techniques are discussed. The uniaxial tensile strain of micro-bridge and biaxial tensile strain of microdisk obtained by strain concentration method of Ge thin films with a thickness of 350 nm reach 4. 9% and 1. 9%,respectively. Such a large strain will adjust Ge into a direct bandgap material,which is suitable for the research and development of the Ge laser.
Tensile strained Ge thin films which are compatible with Si integrated circuits technology have attracted great attention due to their potential applications in optoelectric devices such as photodetector,modulator,and especially light emitting devices. However, introducing a controllable and large tensile strain to Ge thin films is a challenge. The research progresses of fabrication techniques of tensilely strained Ge thin films are reviewed. The fabrication process flow and test results of various approaches including epitaxy technology,strain transfer technology,strain concentration technology and mechanical strain technology to apply tensile strain to Ge thin films are introduced,respectively. And the advantages and disadvantages of these techniques are discussed. The uniaxial tensile strain of micro-bridge and biaxial tensile strain of microdisk obtained by strain concentration method of Ge thin films with a thickness of 350 nm reach 4. 9% and 1. 9%,respectively. Such a large strain will adjust Ge into a direct bandgap material,which is suitable for the research and development of the Ge laser.
引文
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[14]WIRTHS S,STANGE D,PAMPILLN M,et al.High-k gate stacks on low bandgap tensile strained Ge and Ge Sn alloys for field-effect transistors[J].ACS Applied Materials&Interfaces,2015,7(1):62-67.
[15]BAI Y,LEE K E K,CHENG C W,et al.Growth of highly tensile-strained Ge on relaxed InxGa1-xAs by metalorganic chemical vapor deposition[J].Journal of Applied Physics,2008,104(8):084518-1-084518-9.
[16]HOSHINA Y,YAMADA A,KONAGAI M.Growth and characterization of highly tensile-strained Ge on InxGa1-xAs virtual substrate by solid source molecular beam epitaxy[J].Japanese Journal of Applied Physics,2009,48(11):111102-1-111102-4.
[17]HUO Y J,LIN H,CHEN R,et al.Strong enhancement of direct transition photoluminescence with highly tensile-strained Ge grown by molecular beam epitaxy[J].Applied Physics Letters,2011,98(1):011111-1-011111-3.
[18]NAM D,SUKHDEO D,ROY A,et al.Strained germanium thin film membrane on silicon substrate for optoelectronics[J].Optics Express,2011,19(27):25866-25872.
[19]GHRIB A,KERSAUSON M,KURDI M,et al.Control of tensile strain in germanium waveguides through silicon nitride layers[J].Applied Physics Letters,2012,100(20):201104-1-201104-4.
[20]GHRIB A,KURDI M,KERSAUSON M,et al.Tensilestrained germanium microdisks[J].Applied Physics Letters,2013,102(22):221112-1-221112-4.
[21]GHRIB A,KURDI M,PROST M,et al.All-around Si N stressor for high and homogeneous tensile strain in germanium microdisk cavities[J].Advanced Optical Materials,2015,3(3):353-358.
[22]KURDI M,PROST M,GHRIB A,et al.Direct band gap germanium microdisks obtained with silicon nitride stressor layers[J].ACS Photonics,2016,3:443-448.
[23]MILLAR R,GALLACHER K,FRIGERIO J,et al.Analysis of Ge micro-cavities with in-plane tensile strains above 2%[J].Optics Express,2016,24(4):4365-4374.
[24]SESS M,GEIGER R,MINAMISAWA R,et al.Analysis of enhanced light emission from highly strained germanium microbridges[J].Nature Photonics,2013,7(6):466-472.
[25]NAM D,SUKHDEO D,KANG J,et al.Strain-induced pseudoheterostructure nanowires confining carriers at room temperature with nanoscale-tunable band profiles[J].Nano Letters,2013,19(7):3118-3123.
[26]SUKHDEO D S,NAM D,KANG J H,et al.Direct bandgap germanium-on-silicon inferred from 5.7%<100>uniaxial tensile strain[J].Photonics Research,2014,2(3):A8-A13.
[27]GASSENQ A,TARDIF S,GUILLOY K,et al.Accurate strain measurements in highly strained Ge microbridges[J].Applied Physics Letters,2016,108(24):241902-1-241902-4.
[28]SUKHDEO D,NAM D,KANG H,et al.Bandgapcustomizable germanium using lithographically determined biaxial tensile strain for silicon-compatible optoelectronics[J].Optics Express,2015,23(13):16740-16749.
[29]GASSENQ A,GUILLOY K,DIAS G O,et al.1.9%bi-axial tensile strain in thick germanium suspended membranes fabricated in optical germanium-on-insulator substrates for laser applications[J].Applied Physics Letters,2015,107(19):191904-1-191904-4.
[30]KURDI M,BERTIN H,MARTINCIC E,et al.Control of direct band gap emission of bulk germanium by mechanical tensile strain[J].Applied Physics Letters,2010,96(4):041909-1-041909-3.
[31]SNCHEZ-PREZ J,BOZTUG C,CHEN F,et al.Direct-bandgap light-emitting germanium in tensilely strained nanomembranes[J].Proceedings of the National Academy of Sciences of the United States of America 2011,108(47):18893-18898.
[2]MICHEL J,LIU J F,KIMERLING L C.High-performance Ge-on-Si photodetectors[J].Nature Photonics,2010,4(8):527-534.
[3]ROTH J E,FIDANER O,SCHAEVITZ R K,et al.Optical modulator on silicon employing germanium quantum wells[J].Optics Express,2007,15(9):5851-5859.
[4]CAMACHO-AGUILERA R,CAI Y,TATEL N,et al.An electrically pumped germanium laser[J].Optics Express,2012,20(10):11316-11320.
[5]DUTT B,SUKHDEO D S,NAM D,et al.Roadmap to an efficient germanium-on-silicon laser:strain vs.n-type doping[J].IEEE Photonics Journal,2012,4(5):2002-2009.
[6]van de WALLE C G.Band lineups and deformation potentials in the model-solid theory[J].Physical Review:B,1989,39(3):1871-1883.
[7]ISHIKAWA Y,WADA K,LIU J F,et al.Strain-induced enhancement of near-infrared absorption in Ge epitaxial layers grown on Si substrate[J].Journal of Applied Physics,2005,98(1):013501-1-013501-9.
[8]BHARGAVA N,COPPINGER M,GUPTA J,et al.Lattice constant and substitutional composition of Ge Sn al-loys grown by molecular[J].Applied Physics Letters,2013,103(4):041908-1-041908-4.
[9]FANG Y Y,TOLLE J,ROUCKA R,et al.Perfectly tetragonal,tensile-strained Ge on Ge1-ySnybuffered Si(100)[J].Applied Physics Letters,2007,90(6):061915-1-061915-4.
[10]FANG Y Y,TOLLE J,TICE J,et al.Epitaxy-driven synthesis of elemental Ge/Si strain-engineered materials and device structures via designer molecular chemistry[J].Chemistry of Materials,2007,19(24):5910-5925.
[11]TAKEUCHI S,SHIMURA Y,NAKATSUKA O,et al.Growth of highly strain-relaxed Ge1-xSnx/virtual Ge by a Sn precipitation controlled compositionally step-graded method[J].Applied Physics Letters,2008,92(23):231916-1-231916-3.
[12]SHIMURA Y,TAKEUCHI S,NAKATSUKA O,et al.Low temperature growth of Ge1-xSnxbuffer layers for tensile-strained Ge layers[J].Thin Solid Films,2010,518:S2-S5.
[13]WIRTHS S,TIEDEMANN T,IKONIC Z,et al.Band engineering and growth of tensile strained Ge/(Si)Ge Sn heterostructures for tunnel field effect transistors[J].Applied Physics Letters,2013,102(19):192103-1-192103-3.
[14]WIRTHS S,STANGE D,PAMPILLN M,et al.High-k gate stacks on low bandgap tensile strained Ge and Ge Sn alloys for field-effect transistors[J].ACS Applied Materials&Interfaces,2015,7(1):62-67.
[15]BAI Y,LEE K E K,CHENG C W,et al.Growth of highly tensile-strained Ge on relaxed InxGa1-xAs by metalorganic chemical vapor deposition[J].Journal of Applied Physics,2008,104(8):084518-1-084518-9.
[16]HOSHINA Y,YAMADA A,KONAGAI M.Growth and characterization of highly tensile-strained Ge on InxGa1-xAs virtual substrate by solid source molecular beam epitaxy[J].Japanese Journal of Applied Physics,2009,48(11):111102-1-111102-4.
[17]HUO Y J,LIN H,CHEN R,et al.Strong enhancement of direct transition photoluminescence with highly tensile-strained Ge grown by molecular beam epitaxy[J].Applied Physics Letters,2011,98(1):011111-1-011111-3.
[18]NAM D,SUKHDEO D,ROY A,et al.Strained germanium thin film membrane on silicon substrate for optoelectronics[J].Optics Express,2011,19(27):25866-25872.
[19]GHRIB A,KERSAUSON M,KURDI M,et al.Control of tensile strain in germanium waveguides through silicon nitride layers[J].Applied Physics Letters,2012,100(20):201104-1-201104-4.
[20]GHRIB A,KURDI M,KERSAUSON M,et al.Tensilestrained germanium microdisks[J].Applied Physics Letters,2013,102(22):221112-1-221112-4.
[21]GHRIB A,KURDI M,PROST M,et al.All-around Si N stressor for high and homogeneous tensile strain in germanium microdisk cavities[J].Advanced Optical Materials,2015,3(3):353-358.
[22]KURDI M,PROST M,GHRIB A,et al.Direct band gap germanium microdisks obtained with silicon nitride stressor layers[J].ACS Photonics,2016,3:443-448.
[23]MILLAR R,GALLACHER K,FRIGERIO J,et al.Analysis of Ge micro-cavities with in-plane tensile strains above 2%[J].Optics Express,2016,24(4):4365-4374.
[24]SESS M,GEIGER R,MINAMISAWA R,et al.Analysis of enhanced light emission from highly strained germanium microbridges[J].Nature Photonics,2013,7(6):466-472.
[25]NAM D,SUKHDEO D,KANG J,et al.Strain-induced pseudoheterostructure nanowires confining carriers at room temperature with nanoscale-tunable band profiles[J].Nano Letters,2013,19(7):3118-3123.
[26]SUKHDEO D S,NAM D,KANG J H,et al.Direct bandgap germanium-on-silicon inferred from 5.7%<100>uniaxial tensile strain[J].Photonics Research,2014,2(3):A8-A13.
[27]GASSENQ A,TARDIF S,GUILLOY K,et al.Accurate strain measurements in highly strained Ge microbridges[J].Applied Physics Letters,2016,108(24):241902-1-241902-4.
[28]SUKHDEO D,NAM D,KANG H,et al.Bandgapcustomizable germanium using lithographically determined biaxial tensile strain for silicon-compatible optoelectronics[J].Optics Express,2015,23(13):16740-16749.
[29]GASSENQ A,GUILLOY K,DIAS G O,et al.1.9%bi-axial tensile strain in thick germanium suspended membranes fabricated in optical germanium-on-insulator substrates for laser applications[J].Applied Physics Letters,2015,107(19):191904-1-191904-4.
[30]KURDI M,BERTIN H,MARTINCIC E,et al.Control of direct band gap emission of bulk germanium by mechanical tensile strain[J].Applied Physics Letters,2010,96(4):041909-1-041909-3.
[31]SNCHEZ-PREZ J,BOZTUG C,CHEN F,et al.Direct-bandgap light-emitting germanium in tensilely strained nanomembranes[J].Proceedings of the National Academy of Sciences of the United States of America 2011,108(47):18893-18898.