P-doped germanium nanowires with Fano-broadening in Raman spectrum

Abstract

The optimized growth conditions for high density germanium (Ge) nanowires and P-doped Ge nanowires on Si (111) substrate were investigated, the phosphorus (P)-doping in Ge nanowires was also characterized. Vapor liquid solid-low pressure chemical vapor deposition (VLS-LPCVD) of Ge nanowires was conducted with different thicknesses of Au film as catalyst, different flow rates of GeH₄ as precursor and PH₃/Ar as co-flow. The morphologies of the Ge nanowires were characterized by scanning electron microscopy (SEM), the P-doping was verified by micro Raman spectroscopy via measuring the P local vibrational peak (342-345 cm^-1) and asymmetric broadening of Ge-Ge vibrational peak (about 300 cm^-1), respectively. The characterization results show that 1 nm thickness of Au catalyst is the most suitable condition among thicknesses of 0.1, 1, 5, and 10 nm for the growth of high density Ge nanowires at 300 and 350 °C, and 0.5 sccm is the best flow rate of PH₃/Ar to grow high density and large scale P-doped Ge nanowires among flow rates of 0.5, 1 and 2 sccm. The P impurity can be doped into Ge nanowires effectively during LPCVD process at 350 °C.

Keywords

germanium / nanowires / LPCVD / doping / VLS

References

[1] Pang Q, Zhang J, Zhang Y, et al. Properties of the Bare, Passivated and Doped Germanium Nanowire: A Density-Functional Theory study[J]. Comp. Mater. Sci., 2010, 49: 682-690.

[2] Li L, Fang X, Chew H G, et al. Crystallinity-Controlled Germanium Nanowire Arrays: Potential Field Emitters[J]. Adv. Funct. Mater., 2008, 18: 1 080-1 088.

[3] Fukutani K, Ishida Y, Tanji K, et al. Nanowire Array fabricated by Al-Ge Phase Separation[J]. Thin Solid Films, 2007, 515: 4 629-4 635.

[4] He L, Li Z C, Zhang Z J. Rapid, Low-Temperature Synthesis of Singlecrystalline Co3O4 Nanorods on Silicon Substrates on a large Scale[J]. Nanotechnology, 2008, 19: 155.

[5] Kamenev B V, Sharma V, Tsybeskov L, et al. Optical Properties of Ge Nanowires grown on Si (100) and (111) Substrates: Nanowire-Substrate Heterointerfaces[J]. Phys. Stat. Sol., 2005, 14: 2 753-2 758.

[6] Dayeh S A, Picraux S T. Direct Observation of Nanoscale Size Effects in Ge Semiconductor Nanowire Growth[J]. Nano Lett., 2010, 10: 4 032-4 039.

[7] Aksoy B, Coskun S, Kucukyildiz S, et al. Transparent, Highly Flexible, All Nanowire Network Germanium Photodetectors[J]. Nanotechnology, 2012, 23: 325.

[8] Collins G, Kolesnik M, Krstic V, et al. Germanium Nanowire Synthesis from Fluorothiolate-Capped Gold Nanoparticles in Supercritical Carbon Dioxide[J]. Chem. Mater., 2010, 22: 5 235-5 243.

[9] Barrett C A, Geaney H, Gunning R D, et al. Perpendicular Growth of Catalyst-free Germanium Nanowire Arrays[J]. Chem. Commun., 2011, 47: 3 843-3 845.

[10] Ko Y D, Kang J G, Lee G H, et al. Sn-Induced low-Temperature Growth of Ge Nanowire Electrodes with a large Lithium Storage Capacity[J]. Nanoscale, 2011, 3: 3 371-3 375.

[11] Gopakumar G, Wang X, Lin L, et al. Lithium-Doped Germanium Nanowire? Experimental and Theoretical Indication[J]. J. Phys. Chem. C, 2009, 113: 10 858-10 867.

[12] Tutuc E, Appenzeller J, Reuter M C, et al. Realization of a Linear Germanium Nanowire p-n Junction[J]. Nano Lett., 2006, 62: 2 070-2 074.

[13] Chockla A M, Korgel B A. Seeded Germanium Nanowire Synthesis in Solution[J]. J. Mater. Chem., 2009, 19: 996-1 001.

[14] Wu Y Y, Yang P D. Germanium Nanowire Growth via Simple Vapor Transport[J]. Chem. Mater., 2000, 12: 605-607.

[15] Polyakov B, Daly B, Prikulis J, et al. High-Density Arrays of Germanium Nanowire Photoresistors[J]. Adv. Mater., 2006, 18: 1 812-1 816.

[16] Jagannathan H, Deal M, Nishi Y, et al. Templated Germanium Nanowire Synthesis Using Oriented Mesoporous Organosilicate Thin Films[J]. J. Vac. Sci. Technol. B, 2006, 24: 2 220-2 224.

[17] Audoit G, Mhuircheartaigh É N, Lipson S M, et al. Strain Induced Photoluminescence from Silicon and Germanium Nanowire Arrays[J]. J. Mater. Chem., 2005, 15: 4 809-4 815.

[18] Li C B, Usami K, Yamahata G, et al. Position-Controllable Ge Nanowires Growth on Patterned Au Catalyst Substrate[J]. Appl. Phys. Express, 2009, 2: 015.

[19] Redcay C J, Englandera O. Germanium Nanowire Synthesis Using a Localized Heat Source and a Comparison to Synthesis in a Uniform Temperature Environment[J]. J. Mater. Res., 2011, 26: 2 215-2 223.

[20] Romanyuk K, Myslivecek J, Cherepanov V, et al. Optimized Ge Nanowire Arrays on Si by Modified Surfactant Mediated Epitaxy[J]. Phys. Rev. B, 2007, 75: 241309.

[21] Li C B, Usami K, Mizuta H, et al. Vapor-Solid-Solid Radial Growth of Ge Nanowire[J]. J. Appl. Phys., 2009, 106: 046102.

[22] Simanullang M, Usami K, Kodera T, et al. Germanium Nanowires with 3-nm-Diameter Prepared by Low Temperature Vapour-Liquid-Solid Chemical Vapour Deposition[J]. J. Nanosci. Nanotechnol., 2011, 11: 8 163-8 168.

[23] Tutuc E, Appenzeller J, Reuter M C, et al. Realization of a Linear Germanium Nanowire p-n Junction[J]. Nano Lett., 2006, 6: 2 070-2 074.

[24] Ragan R, Ahn C C, Atwater H A. Nonlithographic Epitaxial SnxGe1-x Dense Nanowire Arrays Grown on Ge(001)[J]. Appl. Phys. Lett., 2003, 82: 3 439-3 441.

[25] Tuan H Y, Lee D C, Hanrath T, et al. Germanium Nanowire Synthesis: An Example of Solid-Phase Seeded Growth with Nickel Nanocrystals[J]. Chem. Mater., 2005, 17: 5 705-5 711.

[26] Greytak A B, Lauhon L J, Gudiksen S M, et al. Growth and transport Properties of Complementary Germanium Nanowire Field-Effect Transistors[J]. Appl. Phys. Lett., 2004, 84: 4 176-4 178.

[27] Erts D, Polyakov B, Daly B, et al. High Density Germanium Nanowire Assemblies: Contact Challenges and Electrical Characterization[J]. J. Phys. Chem. B, 2006, 110: 820-827.

[28] Li C B, Usami K, Muraki T, et al. The Impacts of Surface Conditions on the Vapor-Liquid-Solid Growth of Germanium Nanowires on Si (100) Substrate[J]. Appl. Phys. Lett., 2008, 93: 041917.

[29] Jagannathan H, Deal M, Nishi Y, et al. Nature of Germanium Nanowire Heteroepitaxy on Silicon Substrate[J]. J. Appl. Phys., 2006, 100: 024.

[30] Quitoriano N J, Kamins T I. Lateral, Ge Nanowire Growth on SiO₂[J]. Nanotechnology, 2011, 22: 065.

[31] Marshall A, Mclntyre P C. Size Effects in Vapor-Solid-Solid Ge Nanowire Growth with a Ni-based Catalyst[J]. J. Appl. Phys., 2012, 112: 054.

[32] Chang H Y, Tsybeskov L, Sharma S, et al. Photoluminescence and Raman Scattering in Axial Si/Ge Nanowire Heterojunctions[J]. Appl. Phys. Lett., 2009, 95: 133.

[33] Li C B, Usami K, Mizuta H, et al. Growth of Ge-Si Nanowire Heterostructures via chemical Vapor Deposition[J]. Thin Solid Films, 2011, 519: 4 174-4 176.

[34] Olego D, Cardona M. Self-Energy of the optical Phonons of Heavily Doped p-GaAs and p-Ge[J]. Phys. Rev. B, 1981, 23: 6 592-6 602.

[35] Choi W K, Ng V, Ng S P, et al. Raman Characterization of Germanium Nanocrystals in Amorphous Silicon Oxide Films Synthesized by Rapid Thermal Annealing[J]. J. Appl. Phys., 1999, 86: 1 398-1 403.

[36] Bottani C E, Mantini C, Milani P, et al. Raman, Optical-Absorption, and Transmission Electron Microscopy Study of Size Effects in Germanium Quantum Dots[J]. Appl. Phys. Lett., 1996, 69: 2 409-2 411.

[37] Wakaki M, Iwase M, Show Y, et al. Raman Spectroscopy of Germanium Films deposited with Cluster-Beam Technique[J]. Phys. B, 1996, 219-220: 535-537.