Impact of strain relaxation on the growth rate of heteroepitaxial germanium tin binary alloy

Pedram Jahandar; Maksym Myronov

doi:10.1088/1674-4926/24030002

J. Semicond. > 2024, Volume 45 > Issue 10 > 102101

ARTICLES

Impact of strain relaxation on the growth rate of heteroepitaxial germanium tin binary alloy

Pedram Jahandar and Maksym Myronov

+ Author Affiliations

Corresponding author: Pedram Jahandar, P.Jahandar@warwick.ac.uk

DOI: 10.1088/1674-4926/24030002CSTR: 32376.14.1674-4926.24030002

Abstract: The growth of high-quality germanium tin (Ge_1–ySn_y) binary alloys on a Si substrate using chemical vapor deposition (CVD) techniques holds immense potential for advancing electronics and optoelectronics applications, including the development of efficient and low-cost mid-infrared detectors and light sources. However, achieving precise control over the Sn concentration and strain relaxation of the Ge_1–ySn_y epilayer, which directly influence its optical and electrical properties, remain a significant challenge. In this research, the effect of strain relaxation on the growth rate of Ge_1–ySn_y epilayers, with Sn concentration >11at.%, is investigated. It is successfully demonstrated that the growth rate slows down by ~55% due to strain relaxation after passing its critical thickness, which suggests a reduction in the incorporation of Ge into Ge_1–ySn_y growing layers. Despite the increase in Sn concentration as a result of the decrease in the growth rate, it has been found that the Sn incorporation rate into Ge_1–ySn_y growing layers has also decreased due to strain relaxation. Such valuable insights could offer a foundation for the development of innovative growth techniques aimed at achieving high-quality Ge_1–ySn_y epilayers with tuned Sn concentration and strain relaxation.

Key words: GeSn, germanium tin, strain relaxation, group Ⅳ semiconductor, chemical vapour deposition, CVD

References

[1]	Johnson E R, Christian S M. Some properties of germanium-silicon alloys. Phys Rev, 1954, 95, 560 doi: 10.1103/PhysRev.95.560
[2]	Göbel E O, Ploog K. Fabrication and optical properties of semiconductor quantum wells and superlattices. Prog Quantum Electron, 1990, 14, 289 doi: 10.1016/0079-6727(90)90001-E
[3]	Joyce B A. Materials fundamentals of molecular beam epitaxy. Adv Mater, 1993, 5, 773 doi: 10.1002/adma.19930051028
[4]	Gupta S, Magyari-Köpe B, Nishi Y, et al. Achieving direct band gap in germanium through integration of Sn alloying and external strain. J Appl Phys, 2013, 113, 73707 doi: 10.1063/1.4792649
[5]	Wirths S, Buca D, Mantl S. Si–Ge–Sn alloys: From growth to applications. Prog Cryst Growth Charact Mater, 2016, 62, 1 doi: 10.1016/j.pcrysgrow.2015.11.001
[6]	Lieten R R, Maeda T, Jevasuwan W, et al. Tensile-strained GeSn metal–oxide–semiconductor field-effect transistor devices on Si(111) using solid phase epitaxy. Appl Phys Express, 2013, 6, 101301 doi: 10.7567/APEX.6.101301
[7]	Guo P F, Han G Q, Gong X, et al. Ge_0.97Sn_0.03 p-channel metal-oxide-semiconductor field-effect transistors: Impact of Si surface passivation layer thickness and post metal annealing. J Appl Phys, 2013, 114, 044510 doi: 10.1063/1.4816695
[8]	Eckhardt C, Hummer K, Kresse G. Indirect-to-direct gap transition in strained and unstrained Sn_xGe_{1– x} alloys. Phys Rev B, 2014, 89, 165201 doi: 10.1103/PhysRevB.89.165201
[9]	Zheng J, Liu Z, Xue C L, et al. Recent progress in GeSn growth and GeSn-based photonic devices. J Semicond, 2018, 39, 061006 doi: 10.1088/1674-4926/39/6/061006
[10]	Oguz S, Paul W, Deutsch T F, et al. Synthesis of metastable, semiconducting Ge-Sn alloys by pulsed UV laser crystallization. Appl Phys Lett, 1983, 43, 848 doi: 10.1063/1.94524
[11]	Soref R A, Friedman L. Direct-gap Ge/GeSn/Si and GeSn/Ge/Si heterostructures. Superlattices Microstruct, 1993, 14, 189 doi: 10.1006/spmi.1993.1122
[12]	Gurdal O, Desjardins P, Carlsson J R A, et al. Low-temperature growth and critical epitaxial thicknesses of fully strained metastable Ge_{1– x}Sn_x (x≤0.26) alloys on Ge(001)₂ × 1. J Appl Phys, 1998, 83, 162 doi: 10.1063/1.366690
[13]	Mosleh A, Ghetmiri S A, Conley B R, et al. Material characterization of Ge_{1− x}Sn_xAlloys grown by a commercial CVD system for optoelectronic device applications. J Electron Mater, 2014, 43, 938 doi: 10.1007/s11664-014-3089-2
[14]	Wang W, Zhou Q, Dong Y, et al. Critical thickness for strain relaxation of Ge_1–_i>xSn_x (x ≤ 0.17) grown by molecular beam epitaxy on Ge(001). Appl Phys Lett, 2015, 106, 232106 doi: 10.1063/1.4922529
[15]	Gencarelli F, Vincent B, Demeulemeester J, et al. Crystalline properties and strain relaxation mechanism of CVD grown GeSn. ECS J Solid State Sci Technol, 2013, 2, P134 doi: 10.1149/2.011304jss
[16]	Bhargava N, Coppinger M, Prakash Gupta J, et al. Lattice constant and substitutional composition of GeSn alloys grown by molecular beam epitaxy. Appl Phys Lett, 2013, 103, 041908 doi: 10.1063/1.4816660
[17]	Takeuchi S, Sakai A, Yamamoto K, et al. Growth and structure evaluation of strain-relaxed Ge_{1– x}Sn_x buffer layers grown on various types of substrates. Semicond Sci Technol, 2007, 22, S231 doi: 10.1088/0268-1242/22/1/S54
[18]	Takeuchi S, Shimura Y, Nakatsuka O, et al. Growth of highly strain-relaxed Ge_{1– x}Sn_x/virtual Ge by a Sn precipitation controlled compositionally step-graded method. Appl Phys Lett, 2008, 92, 231916 doi: 10.1063/1.2945629
[19]	Takeuchi S, Sakai A, Nakatsuka O, et al. Tensile strained Ge layers on strain-relaxed Ge_1–xSn_x/virtual Ge substrates. Thin Solid Films, 2008, 517, 159 doi: 10.1016/j.tsf.2008.08.068
[20]	Wirths S, Tiedemann A T, Ikonic Z, et al. Band engineering and growth of tensile strained Ge/(Si)GeSn heterostructures for tunnel field effect transistors. Appl Phys Lett, 2013, 102, 192103 doi: 10.1063/1.4805034
[21]	Weisshaupt D, Jahandar P, Colston G, et al. Impact of Sn segregation on Ge_{1− x}Sn_x epi-layers growth by RP-CVD. 2017 40th International Convention on Information and Communication Technology, Electronics and Microelectronics (MIPRO), 2017, 43 doi: 10.23919/MIPRO.2017.7973388
[22]	Jahandar P, Weisshaupt D, Colston G, et al. The effect of Ge precursor on the heteroepitaxy of Ge_{1– x}Sn_x epilayers on a Si (001) substrate. Semicond Sci Technol, 2018, 33, 034003 doi: 10.1088/1361-6641/aa9e7e
[23]	Lu Low K, Yang Y, Han G Q, et al. Electronic band structure and effective mass parameters of Ge_{1- x}Sn_x alloys. J Appl Phys, 2012, 112, 103106 doi: 10.1063/1.4765736
[24]	Tonkikh A A, Eisenschmidt C, Talalaev V G, et al. Pseudomorphic GeSn/Ge(001) quantum wells: Examining indirect band gap bowing. Appl Phys Lett, 2013, 103, 032106 doi: 10.1063/1.4813913
[25]	Dutt B, Lin H, Sukhdeo D S, et al. Theoretical analysis of GeSn alloys as a gain medium for a Si-compatible laser. IEEE J Sel Top Quantum Electron, 2013, 19, 1502706 doi: 10.1109/JSTQE.2013.2241397
[26]	Ionescu A M, Riel H. Tunnel field-effect transistors as energy-efficient electronic switches. Nature, 2011, 479, 329 doi: 10.1038/nature10679
[27]	Kotlyar R, Avci U E, Cea S, et al. Bandgap engineering of group IV materials for complementary n and p tunneling field effect transistors. Appl Phys Lett, 2013, 102, 113106 doi: 10.1063/1.4798283
[28]	Olesinski R W, Abbaschian G J. The Ge−Sn (Germanium−Tin) system. Bull Alloy Phase Diagr, 1984, 5, 265 doi: 10.1007/BF02868550
[29]	Fleurial J P, Borshchevsky A. Si-Ge-metal ternary phase diagram calculations. J Electrochem Soc, 1990, 137, 2928 doi: 10.1149/1.2087101
[30]	Zaima S, Nakatsuka O, Taoka N, et al. Growth and applications of GeSn-related Group-IV semiconductor materials. Sci Technol Adv Mater, 2015, 16, 043502 doi: 10.1088/1468-6996/16/4/043502

Fig. 1. (Colour online) Theoretical calculations of h_c for Ge_1–ySn_y films grown on Si substrate via a relaxed Ge-VS using the People Bean (P–B) model and the Matthew Blakeslee (M–B) model^[13]. Experimental data collected from this work as well as previous research are included^[14−16].

DownLoad: Full-Size Img PowerPoint

Fig. 2. (Colour online) (a) HR-XRD ω–2θ coupled scans for Ge_1–ySn_y epilayers grown with different growth times on Si (001) via Ge-VS. Symmetric and asymmetric RSMs for Ge_1–ySn_y grown with different growth times on Si (001) via Ge-VS of (b) 79 nm thick Ge_0.884Sn_0.116 grown for 8 min, (c) 95 nm thick Ge_0.884Sn_0.116 grown for 10 min, (d) 128 nm thick Ge_0.882Sn_0.118 grown for 15 min, and (e) 150 nm thick Ge_0.878Sn_0.122 grown for 20 min. The Sn concentration for each of these samples was measured from RSMs and using the modified Vegard’s law. The thicknesses of these epilayers are measured using either thickness fringes appeared in their HR-XRD ω–2θ coupled scans or X-TEM images, as shown in the example in Fig. 3(a).

DownLoad: Full-Size Img PowerPoint

Fig. 3. (Colour online) (a) X-TEM image of 150 nm thick Ge_0.878Sn_0.122 grown on Ge-VS. The high resolution lattice resolved X-TEM micrographs of Ge_0.878Sn_0.122/Ge-VS interface as well as surface of Ge_0.878Sn_0.122 epilayer are presented. (b) Relationship between thickness, Sn concentration and total growth rate of Ge_1–ySn_y epilayers. (c) AFM scan of 95 nm thick Ge_0.884Sn_0.116. (d) AFM scan of 128 nm thick Ge_0.882Sn_0.118. (e) AFM scan of 150 nm thick Ge_0.878Sn_0.122. (f) Surface roughness (RMS) of Ge_1–ySn_y epilayers with different thicknesses. Surface roughness increased with the increase in thickness (growth time), particularly after the critical thickness of ~95 nm.

DownLoad: Full-Size Img PowerPoint

Fig. 4. (Colour online) (a) Average growth rate (nm/min) at the given thickness (nm) of the Ge_1–ySn_y and its corresponding growth time (min). As the thickness of the Ge_1–ySn_y increases, the growth rate decreases. (b) Actual data points collected experimentally for average growth rate (nm/min).

DownLoad: Full-Size Img PowerPoint

Fig. 5. (Colour online) The effect of strain relaxation in Ge_1–ySn_y epilayers on their growth rate. The growth rate at given strain relaxation state was estimated using the fitted line to the actual data points given in Fig. 4. In-plane and out-of-plane strain were calculated by Eqs. (1) and (2).

DownLoad: Full-Size Img PowerPoint

Table 1. Summary of effects of strain relaxation on the Sn concentration and growth rate of Ge_1–ySn_y epilayers grown at 260 °C and 500 Torr on Si (001) via a relaxed Ge-VS.

Thickness (nm)	In-plane strain (10^–3)	Out-of-plane strain (10^–3)	Average Sn content (at.%)	Average growth rate (nm/min)
29	–15.4	12.1	11.6	9.7
50	–15.6	12.2	11.6	10.0
79	–15.8	12.4	11.6	9.9
95	–15.6	12.3	11.6	9.5
128	–11.1	8.7	11.8	8.5
150	–9.8	7.7	12.2	7.5
150	–9.3	7.3	12.5	7.5

DownLoad: CSV

[1]	Johnson E R, Christian S M. Some properties of germanium-silicon alloys. Phys Rev, 1954, 95, 560 doi: 10.1103/PhysRev.95.560
[2]	Göbel E O, Ploog K. Fabrication and optical properties of semiconductor quantum wells and superlattices. Prog Quantum Electron, 1990, 14, 289 doi: 10.1016/0079-6727(90)90001-E
[3]	Joyce B A. Materials fundamentals of molecular beam epitaxy. Adv Mater, 1993, 5, 773 doi: 10.1002/adma.19930051028
[4]	Gupta S, Magyari-Köpe B, Nishi Y, et al. Achieving direct band gap in germanium through integration of Sn alloying and external strain. J Appl Phys, 2013, 113, 73707 doi: 10.1063/1.4792649
[5]	Wirths S, Buca D, Mantl S. Si–Ge–Sn alloys: From growth to applications. Prog Cryst Growth Charact Mater, 2016, 62, 1 doi: 10.1016/j.pcrysgrow.2015.11.001
[6]	Lieten R R, Maeda T, Jevasuwan W, et al. Tensile-strained GeSn metal–oxide–semiconductor field-effect transistor devices on Si(111) using solid phase epitaxy. Appl Phys Express, 2013, 6, 101301 doi: 10.7567/APEX.6.101301
[7]	Guo P F, Han G Q, Gong X, et al. Ge_0.97Sn_0.03 p-channel metal-oxide-semiconductor field-effect transistors: Impact of Si surface passivation layer thickness and post metal annealing. J Appl Phys, 2013, 114, 044510 doi: 10.1063/1.4816695
[8]	Eckhardt C, Hummer K, Kresse G. Indirect-to-direct gap transition in strained and unstrained Sn_xGe_{1– x} alloys. Phys Rev B, 2014, 89, 165201 doi: 10.1103/PhysRevB.89.165201
[9]	Zheng J, Liu Z, Xue C L, et al. Recent progress in GeSn growth and GeSn-based photonic devices. J Semicond, 2018, 39, 061006 doi: 10.1088/1674-4926/39/6/061006
[10]	Oguz S, Paul W, Deutsch T F, et al. Synthesis of metastable, semiconducting Ge-Sn alloys by pulsed UV laser crystallization. Appl Phys Lett, 1983, 43, 848 doi: 10.1063/1.94524
[11]	Soref R A, Friedman L. Direct-gap Ge/GeSn/Si and GeSn/Ge/Si heterostructures. Superlattices Microstruct, 1993, 14, 189 doi: 10.1006/spmi.1993.1122
[12]	Gurdal O, Desjardins P, Carlsson J R A, et al. Low-temperature growth and critical epitaxial thicknesses of fully strained metastable Ge_{1– x}Sn_x (x≤0.26) alloys on Ge(001)₂ × 1. J Appl Phys, 1998, 83, 162 doi: 10.1063/1.366690
[13]	Mosleh A, Ghetmiri S A, Conley B R, et al. Material characterization of Ge_{1− x}Sn_xAlloys grown by a commercial CVD system for optoelectronic device applications. J Electron Mater, 2014, 43, 938 doi: 10.1007/s11664-014-3089-2
[14]	Wang W, Zhou Q, Dong Y, et al. Critical thickness for strain relaxation of Ge_1–_i>xSn_x (x ≤ 0.17) grown by molecular beam epitaxy on Ge(001). Appl Phys Lett, 2015, 106, 232106 doi: 10.1063/1.4922529
[15]	Gencarelli F, Vincent B, Demeulemeester J, et al. Crystalline properties and strain relaxation mechanism of CVD grown GeSn. ECS J Solid State Sci Technol, 2013, 2, P134 doi: 10.1149/2.011304jss
[16]	Bhargava N, Coppinger M, Prakash Gupta J, et al. Lattice constant and substitutional composition of GeSn alloys grown by molecular beam epitaxy. Appl Phys Lett, 2013, 103, 041908 doi: 10.1063/1.4816660
[17]	Takeuchi S, Sakai A, Yamamoto K, et al. Growth and structure evaluation of strain-relaxed Ge_{1– x}Sn_x buffer layers grown on various types of substrates. Semicond Sci Technol, 2007, 22, S231 doi: 10.1088/0268-1242/22/1/S54
[18]	Takeuchi S, Shimura Y, Nakatsuka O, et al. Growth of highly strain-relaxed Ge_{1– x}Sn_x/virtual Ge by a Sn precipitation controlled compositionally step-graded method. Appl Phys Lett, 2008, 92, 231916 doi: 10.1063/1.2945629
[19]	Takeuchi S, Sakai A, Nakatsuka O, et al. Tensile strained Ge layers on strain-relaxed Ge_1–xSn_x/virtual Ge substrates. Thin Solid Films, 2008, 517, 159 doi: 10.1016/j.tsf.2008.08.068
[20]	Wirths S, Tiedemann A T, Ikonic Z, et al. Band engineering and growth of tensile strained Ge/(Si)GeSn heterostructures for tunnel field effect transistors. Appl Phys Lett, 2013, 102, 192103 doi: 10.1063/1.4805034
[21]	Weisshaupt D, Jahandar P, Colston G, et al. Impact of Sn segregation on Ge_{1− x}Sn_x epi-layers growth by RP-CVD. 2017 40th International Convention on Information and Communication Technology, Electronics and Microelectronics (MIPRO), 2017, 43 doi: 10.23919/MIPRO.2017.7973388
[22]	Jahandar P, Weisshaupt D, Colston G, et al. The effect of Ge precursor on the heteroepitaxy of Ge_{1– x}Sn_x epilayers on a Si (001) substrate. Semicond Sci Technol, 2018, 33, 034003 doi: 10.1088/1361-6641/aa9e7e
[23]	Lu Low K, Yang Y, Han G Q, et al. Electronic band structure and effective mass parameters of Ge_{1- x}Sn_x alloys. J Appl Phys, 2012, 112, 103106 doi: 10.1063/1.4765736
[24]	Tonkikh A A, Eisenschmidt C, Talalaev V G, et al. Pseudomorphic GeSn/Ge(001) quantum wells: Examining indirect band gap bowing. Appl Phys Lett, 2013, 103, 032106 doi: 10.1063/1.4813913
[25]	Dutt B, Lin H, Sukhdeo D S, et al. Theoretical analysis of GeSn alloys as a gain medium for a Si-compatible laser. IEEE J Sel Top Quantum Electron, 2013, 19, 1502706 doi: 10.1109/JSTQE.2013.2241397
[26]	Ionescu A M, Riel H. Tunnel field-effect transistors as energy-efficient electronic switches. Nature, 2011, 479, 329 doi: 10.1038/nature10679
[27]	Kotlyar R, Avci U E, Cea S, et al. Bandgap engineering of group IV materials for complementary n and p tunneling field effect transistors. Appl Phys Lett, 2013, 102, 113106 doi: 10.1063/1.4798283
[28]	Olesinski R W, Abbaschian G J. The Ge−Sn (Germanium−Tin) system. Bull Alloy Phase Diagr, 1984, 5, 265 doi: 10.1007/BF02868550
[29]	Fleurial J P, Borshchevsky A. Si-Ge-metal ternary phase diagram calculations. J Electrochem Soc, 1990, 137, 2928 doi: 10.1149/1.2087101
[30]	Zaima S, Nakatsuka O, Taoka N, et al. Growth and applications of GeSn-related Group-IV semiconductor materials. Sci Technol Adv Mater, 2015, 16, 043502 doi: 10.1088/1468-6996/16/4/043502

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Received: 04 March 2024 Revised: 30 April 2024 Online: Accepted Manuscript: 04 July 2024Uncorrected proof: 09 July 2024Published: 15 October 2024

Article Navigation > Journal of Semiconductors > 2024 > 45(10): 102101

Pedram Jahandar, Maksym Myronov. Impact of strain relaxation on the growth rate of heteroepitaxial germanium tin binary alloy[J]. Journal of Semiconductors, 2024, 45(10): 102101. doi: 10.1088/1674-4926/24030002 ****P Jahandar and M Myronov, Impact of strain relaxation on the growth rate of heteroepitaxial germanium tin binary alloy[J]. J. Semicond., 2024, 45(10), 102101 doi: 10.1088/1674-4926/24030002

Citation:

Pedram Jahandar, Maksym Myronov. Impact of strain relaxation on the growth rate of heteroepitaxial germanium tin binary alloy[J]. Journal of Semiconductors, 2024, 45(10): 102101. doi: 10.1088/1674-4926/24030002 ****

P Jahandar and M Myronov, Impact of strain relaxation on the growth rate of heteroepitaxial germanium tin binary alloy[J]. J. Semicond., 2024, 45(10), 102101 doi: 10.1088/1674-4926/24030002

Citation:

P Jahandar and M Myronov, Impact of strain relaxation on the growth rate of heteroepitaxial germanium tin binary alloy[J]. J. Semicond., 2024, 45(10), 102101 doi: 10.1088/1674-4926/24030002

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Impact of strain relaxation on the growth rate of heteroepitaxial germanium tin binary alloy

DOI: 10.1088/1674-4926/24030002

CSTR: 32376.14.1674-4926.24030002

Department of Physics, University of Warwick, Coventry, CV4 7AL, United Kingdom

More Information

Pedram Jahandar earned his PhD from the University of Warwick after obtaining his Bachelor of Science and Master of Science degrees from King’s College London. He specialises in Group Ⅳ semiconductor CVD epitaxy and device fabrication, and actively applies the latest technological advancements and academic achievements across various industries
Corresponding author: P.Jahandar@warwick.ac.uk
Received Date: 2024-03-04
Revised Date: 2024-04-30

Available Online: 2024-07-04

Abstract

Abstract

The growth of high-quality germanium tin (Ge_1–ySn_y) binary alloys on a Si substrate using chemical vapor deposition (CVD) techniques holds immense potential for advancing electronics and optoelectronics applications, including the development of efficient and low-cost mid-infrared detectors and light sources. However, achieving precise control over the Sn concentration and strain relaxation of the Ge_1–ySn_y epilayer, which directly influence its optical and electrical properties, remain a significant challenge. In this research, the effect of strain relaxation on the growth rate of Ge_1–ySn_y epilayers, with Sn concentration >11at.%, is investigated. It is successfully demonstrated that the growth rate slows down by ~55% due to strain relaxation after passing its critical thickness, which suggests a reduction in the incorporation of Ge into Ge_1–ySn_y growing layers. Despite the increase in Sn concentration as a result of the decrease in the growth rate, it has been found that the Sn incorporation rate into Ge_1–ySn_y growing layers has also decreased due to strain relaxation. Such valuable insights could offer a foundation for the development of innovative growth techniques aimed at achieving high-quality Ge_1–ySn_y epilayers with tuned Sn concentration and strain relaxation.
- GeSn,
- germanium tin,
- strain relaxation,
- group Ⅳ semiconductor,
- chemical vapour deposition,
- CVD

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