Regulating Effect of Substrate Temperature on Sputtering-grown Ge/Si QDs under Low Ge Deposition

Abstract

The effect of deposition temperature on the morphology and optoelectronic performance of Ge/Si QDs grown by magnetron sputtering under low Ge deposition (∼ 4 nm) was investigated by atomic force microscopy, Raman spectroscopy, and photoluminescence (PL) tests. The experimental results indicate that temperatures higher than 750 °C effectively increase the crystallization rate and surface smoothness of the Si buffer layer, and temperatures higher than 600 °C significantly enhance the migration ability of Ge atoms, thus increasing the probability of Ge atoms meeting and nucleating to form QDs on Si buffer layer, but an excessively high temperature will cause the QDs to undergo an Ostwald ripening process and thus develop into super large islands. In addition, some PL peaks were observed in samples containing small-sized, high-density Ge QDs, the photoelectric properties reflected by these peaks were in good agreement with the corresponding structural characteristics of the grown QDs. Our results demonstrate the viability of preparing high-quality QDs by magnetron sputtering at high deposition rate, and the temperature effect is expected to work in conjunction with other controllable factors to further regulate QD growth, which paves an effective way for the industrial production of QDs that can be used in future devices.

Keywords

Ge/Si QDs / deposition temperatures / evolution law / photoelectric performance

References

[1] Rutckaia V, Heyroth F, Schmidt G, et al. Coupling of Germanium Quantum Dots with Collective Sub-radiant Modes of Silicon Nanopillar Arrays[J]. ACS Photonics, 2021, 8: 209-217.

[2] Zhao Y, Li L, Liu S, et al. Germanium Quantum Dot Infrared Photo-detectors Addressed by Self-aligned Silicon Nanowire Electrodes[J]. Nanotechnology, 2020, 31: 145602.1-146502.7.

[3] Palade C, Slav A, Cojocaru O, et al. SiGeSn Quantum Dots in HfO₂ for Floating Gate Memory Capacitors[J]. Coatings, 2022, 12: 348-359.

[4] Parravicini J, Trapani FD, Nelson MD, et al. Quantum Confinement in the Spectral Response of N-doped Germanium Quantum Dots Embedded in an Amorphous Si Layer for Quantum Dot-based Solar Cells[J]. ACS Appl. Nano Mater., 2020, 3: 2813-2821.

[5] Teys SA. Different Growth Mechanisms of Ge by Stranski-Krastanow on Si (111) and (001) Surfaces: An STM Study[J]. Appl Surf. Sci., 2017, 392: 1017-1025.

[6] Itoh Y, Kawashima T, Washio K. Control of Growth Modes by Carbon Mediation in Formation of Ge Quantum Dots on Si(100)[J]. IEEE T. Nanotechnol., 2017, 16: 595-599.

[7] Smagina ZV, Zinovyev VA, Zinovieva AF, et al. Luminescent Properties of Spatially Ordered Ge/Si Quantum Dots Epitaxially Grown on a Pit-patterned “Silicon-on-Insulator” Substrate[J]. J. Lumin., 2022, 249: 119033.1-119033.5.

[8] Samavati A, Mustafa MK, Othaman Z, et al. Ge Nanoislands Grown by Radio Frequency Magnetron Sputtering: Comprehensive Investigation of Surface Morphology and Optical Properties[J]. J. Nanomater., 2015, 16: 101-120.

[9] Otsuka S, Mori T, Morita Y, et al. Epitaxial Growth of Ge Thin Film on Si (001) by DC Magnetron Sputtering[J]. Mat. Sci. Semicon. Proc., 2017, 70: 3-7.

[10] Khelidj H, Portavoce A, Bertoglio M, et al. Ge(Sn) Growth on Si(001) by Magnetron Sputtering[J]. Mater. Today Commun., 2021, 26: 101915-101925.

[11] Peng Y, Miao L, Li C, et al. Improved Thermoelectric Property of B-doped Si/Ge Multilayered Quantum Dot Films Prepared by RF Magnetron Sputtering[J]. Jpn. J. Appl. Phys., 2018, 57: 01AF03.1-01AF03.5.

[12] Shu QJ, Wang RF, Yang J, et al. Microstructure and Optical Response Optimization of Ge/Si Quantum Dots Transformed from the Sputtering-Grown Ge Thin Film by Manipulating the Thermal Annealing[J]. Nanotechnology, 2018, 29: 095601.1-0956.9.

[13] Shu QJ, Yang J, Chi QB, et al. Structure and Optical Properties of Ge/Si Quantum Dots Formed by Driving the Evolution of Ge Thin Films via Thermal Annealing[J]. Jpn. J. Appl. Phys., 2018, 57: 045602.1-045602.8.

[14] People R. Indirect Band Gap of Coherently Strained GexSi1-x Bulk Alloys on Silicon Substrates[J]. Phys. Rev. B, 1985, 32: 1405-1408.

[15] Lee SW, Chen HC, Chen LJ, et al. Effects of Low-temperature Si Buffer Layer Thickness on the Growth of SiGe by Molecular Beam Epitaxy[J]. J. Appl. Phys., 2002, 92: 6880-6885.

[16] Pan H, Wang C, Yang J, et al. Growth Control of Ge/Si Quantum Dots[J]. J. Infrared Millim. W., 2012, 31: 416-420.

[17] Xu Y, Wang C, Chen S, et al. Improved Quality of Selective Area Epitaxial Growth of Ge Film on Si Substrate by Inserting Si Buffer Layer[J]. Semiconductor Technology, 2019, 44: 297-301.

[18] Boucaud P, Sauvage S, Elkurdi M, et al. Optical Recombination from Excited States in Ge/Si Self-assembled Quantum Dots[J]. Phys. Rev. B, 2001, 64: 155310.1-155310.6.

[19] Kucherenko IV, Vinogradov VS, Melnik NN, et al. Effect of Interdiffusion and Quantum Confinement on Raman Spectra of the Ge/Si(100) Heterostructures with Quantum Dots[J]. Physics, 2009, 40: 123-125.

[20] Gouadec G, Colomban P. Raman Spectroscopy of Nanostructures and Nanosized Materials[J]. J. Raman Spectrosc., 2007, 38: 598-603.

[21] He L, Xiong B, Zhou P, et al. P-doped Germanium Nanowires with Fano-broadening in Raman Spectrum[J]. J. Wuhan Univ. Technol. -Mater. Sci. Ed., 2016, 31(1): 52-57.

[22] Shklyaev AA, Budazhapova AE. Ge Deposition on Si(100) in the Conditions Close to Dynamic Equilibrium between Islands Growth and Their Decay[J]. Appl Surf. Sci., 2016, 360: 1023-1029.

[23] Adnane B, Karlsson KF, Hansson GV, et al. Spatially Direct and Indirect Transitions of Self-assembled GeSi/Si Quantum Dots Studied by Photoluminescence Excitation Spectroscopy[J]. Appl. Phys. Lett., 2010, 96: 181107.1-181107.4.

[24] Vatankhah C, Ebadi A. Quantum Size Effects on Effective Mass and Band Gap of Semiconductor Quantum Dots[J]. Research Journal of Recent Sciences, 2013, 2: 21-24.

[25] Ji ZM, Luo GW, Li SS. Interface-engineering Enhanced Light Emission from Si/Ge Quantum Dots[J]. New J. Phys., 2020, 22: 093037.1-093037.15.