CC BY
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i l St. Petersburg Polytechnic University Journal. Physics and Mathematics. 2022 Vol. 15, No. 3.3 Научно-технические ведомости СПбГПУ. Физико-математические науки. 15 (3.3) 2022
Conference materials UDC 538.958
DOI: https://doi.org/10.18721/JPM.153.331
Analysis of characteristics of InGaAs/GaAs microdisk lasers bonded onto silicon board
A. S. Dragunova 1H, N. V. Kryzhanovskaya 1 2, E. I. Moiseev ', F. I. Zubov 1 2, N. A. Kalyuzhnyy 3, S. A. Mintairov 3, A. M. Nadtochiy 1 3, Yu. A. Guseva 3, M. M. Kulagina 3, A. E. Zhukov 1
1 HSE University, St. Petersburg, Russia; 2 Alferov University, St. Petersburg, Russia; 3 Ioffe Institute, St Petersburg, Russia H [email protected]
Abstract. In this work we study characteristics of the III-V microdisk lasers bonded onto silicon board. The bonding of microdisk lasers to the silicon substrate reduces their thermal resistance. Here we show improvement in output power, lasing threshold, dynamic characteristics and energy consumption in microdisk lasers with diameters of 31 ^m and 19 ^m by comparison of the characteristics obtained before and after bonding. Also, estimation of energy-to-data ratio was performed at 13 °C and 20 °C for a 19 ^m microdisk lasers after bonding.
Keywords: hybrid integration, microlaser, quantum well dots, energy-to-data ratio, thermal resistance
Funding: This study was supported by Russian Science Foundation grant No. 18-12-00287, https://rscf.ru/project/18-12-00287/. Support of optical measurements was implemented in the framework of the Basic Research Program at the National Research University Higher School of Economics (HSE University).
Citation: Dragunova A. S., Kryzhanovskaya N. V., Moiseev E. I., Zubov F. I., Kalyuzhnyy N. A., Mintairov S. A., Nadtochiy A. M., Guseva Yu. A., Kulagina M. M., Zhukov A. E., Analysis of characteristics of InGaAs/GaAs microdisk lasers bonded onto silicon board. St. Petersburg State Polytechnical University Journal. Physics and Mathematics, 15 (3.3) (2022) 163-166. DOI: https://doi.org/10.18721/jPM.153.331
This is an open access article under the CC BY-NC 4.0 license (https://creativecommons. org/licenses/by-nc/4.0/)
Материалы конференции УДК 538.958
DOI: https://doi.org/10.18721/JPM.153.331
Анализ характеристик InGaAs/GaAs микродисковых лазеров перенесенных на кремниевую подложку
А. С. Драгунова 1Н, Н. В. Крыжановская 1 2, Э. И. Моисеев 1, Ф. И. Зубов 1 2, Н. А. Калюжный 3, С. А. Минтаиров 3, А. М. Надточий 1 3, Ю. А. Гусева 3, М. М. Кулагина 3, А. Е. Жуков 1
1 Национальный исследовательский университет «Высшая школа экономики», Санкт-Петербург, Россия; 2 Академический университет им. Ж. И. Алфёрова, Санкт-Петербург, Россия; 3 Физико-технический институт им. А. Ф. Иоффе, Санкт-Петербург, Россия
Аннотация. В данной работе исследуются характеристики микродисковых лазеров, перенесенных на кремниевую подложку. Перенос микродисковых лазеров на кремниевую подложку снижает их тепловое сопротивление, что приводит к улучшению порога генерации, выходной оптической мощности, динамических характеристик и
© Dragunova A. S., Kryzhanovskaya N. V., Moiseev E. I., Zubov F. I., Kalyuzhnyy N. A., Mintairov S. A., Nadtochiy A. M., Guseva Yu. A., Kulagina M. M., Zhukov A. E., 2022. Published by Peter the Great St.Petersburg Polytechnic University.
энергопотребления в микродисковых лазерах диаметром 19 мкм и 31 мкм.
Ключевые слова: гибридная интеграция, микролазер, квантовые яма-точки, энергопотребление, тепловое сопротивление
Финансирование: Исследование выполнено при поддержке гранта РНФ18-12-00287, https://rscf.ru/project/18-12-00287/. Оптические измерения осуществлены в рамках Программы фундаментальных исследований НИУ ВШЭ.
Ссылка при цитировании: Драгунова А. С., Крыжановская Н. В., Моисеев Э. И., Зубов Ф. И., Калюжный Н. А., Минтаиров С. А., Надточий А. М., Гусева Ю. А., Кулагина М. М., Жуков А. Е., Анализ характеристик InGaAs/GaAs микродисковых лазеров перенесенных на кремниевую подложку // Научно-технические ведомости СПбГПУ. Физико-математические науки. 2022. Т. 15. № 3.3. C. 163-166. DOI: https:// doi.org/10.18721/JPM.153.331
Статья открытого доступа, распространяемая по лицензии CC BY-NC 4.0 (https:// creativecommons.org/licenses/by-nc/4.0/)
Introduction
In recent years, much attention has been paid to the development of microlasers based on III-V materials, which could be placed on a silicon substrate and thus allow the integration of light emitting devices with elements of silicon microelectronics and/or silicon photonics [1]. Whispering gallery mode (WGM) microlasers, such as microdisk and microring lasers, are one of the promising microlasers due to the simplicity of their manufacture, high quality factor and low optical losses. It is known [2-4], that thermal resistance increases with decreasing laser cavity size. This effect is quite critical for small devices such as microdisk lasers (MDL), because it has a great influence on their characteristics and performance due to various temperature-dependent processes [5]. It was shown in work [6] that the bonding of microdisk lasers to a silicon substrate improve thermal resistance. In [7] was reported that thermal resistance of 31 цш GaAs microdisk laser bonded on Si board reduces from 0.59 to 0.32 K/mW.
In this work we analyze the effect of reducing thermal resistance on output power, high-frequency characteristics, modulation properties and energy-to-data ratio (EDR) in microdisk lasers.
Materials and Methods
The laser heterostructure was grown by metalorganic vapour-phase epitaxy on an n±GaAs substrate misoriented by 6° toward [111] direction. The laser active region consists of 6 layers of InGaAs/GaAs quantum well-dots separated from each other with 40 nm thick GaAs spacer layers. The active region was placed at the center of an undoped GaAs waveguide with a thickness of 0.78 цш. The waveguide was clamped between two Al04Ga06As cladding layers 1.5 цш thick doped with p- and n-types.
Microdisk lasers with a diameter of 19 and 31 цш were formed by photolithography and dry etching through the active region and two cladding layers to the substrate. The side walls of the microdisk lasers were not passivated. The n-contact was formed on the back surface of a GaAs substrate thinned to ~ 100 цш. Round-shaped AgMn/Ni/Au p-contacts were formed individually to each microdisk on top of p±GaAs top layer (Fig. 1, a). Then the substrate with ready-made microdisk lasers was cleaved onto chips containing 10 microlasers each.
The thermocompression bonding of microdisk lasers on the silicon surface was performed using a Finetech FINEPLACER lambda2 die bonder (Fig. 1, b, с). Electroluminescence was collected with a x50 Mitutoyo M Plan Apo NIR objective and detected by a Yokogawa AQ6370C optical spectrum analyzer or by Thorlabs FDG1010 1^1 cm2 photodiode. Dynamic characteristics were carried out using a New Focus 1434 photodetector with the range from 50 MHz to 20 GHz and an Agilent E8364B network analyzer.
© Драгунова А. С., Крыжановская Н. В., Моисеев Э. И., Зубов Ф. И., Калюжный Н. А., Минтаиров С. А., Надточий А. М., Гусева Ю. А., Кулагина М. М., Жуков А. Е., 2022. Издатель: Санкт-Петербургский политехнический университет Петра Великого.
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Physical optics
Fig. 1. Image of microdisk laser obtained by scanning electron microscopy (a), top-view of microdisk lasers placed on Si board in infra-red illumination during thermocompression bonding (b), top-view
of chip with bonded microdisk lasers on Si board (c)
Results and Discussion
Characteristics of the microdisk lasers with a diameter of 19 and 31 ^m were compared before and after bonding. Thermal resistance of bonded MDL decreases in 2.3 and 1.8 times for 19 ^m and 31 ^m, respectively. The decrease in thermal resistance in microdisk lasers bonded onto a silicon substrate is due to the higher thermal conductivity of the substrate, as well as to a decrease in the thickness of the intermediate layers. The threshold current after bonding decreased from 9.4 to 7.6 mA for 19 ^m microdisk and from 21.4 to 17.4 for 31 ^m microdisk (Fig. 2, a). Better heat removal from the active region results in the higher output optical power, slope of dependence of optical power on bias current and thermal roll-over.
a)
i
5
o = a.
b)
-Q
t
Bi
a
13C 20C
Current, mA
Current, mA
Fig. 2. The output power versus the injection current of 31 ^m MDL before and after bonding (a). The dependence of EDR on the bias current for 13 °C and 20 °C and the 3dB bandwidth versus the
pumping current (inset) for 19 ^m MDL (b)
We also observe improvement in dynamic characteristics of the bonded lasers. The 3dB modulation bandwidth /3dB) of 6.9 GHz and 8 GHz for 19 ^m in diameter device was obtained 20 °C and 13 °C degrees, respectively (inset in Fig.2, b). A noticeable dependence of the peak bandwidth on temperature indicates that the microlaser overheating has a significant effect on its dynamic performance. To estimate the energy efficiency of the microdisk laser intended for optical data transmission one can use energy-to-data ration (EDR), i.e. the electrical energy consumed per bit of transmitted information, EDR = UI/B, where U — is voltage, I — bias current, B — bit rate [8]. The value of bit rate (B) can be estimate as twice the modulation bandwidth B = 2/3dB. The smallest EDR value of 2.5 pJ/bit is achieved in 10—15 mA bias current range. At the current of maximum /3dB (25 mA) for 13 °C the EDR value is 4 pJ/bit.
Conclusion
In this work we study characteristics of the III-V microdisk lasers bonded onto silicon board. The bonding of microdisk lasers to a silicon substrate reduces their thermal resistance. Here
we show improvement in output power, lasing threshold, dynamic characteristics and energy consumption in microdisk lasers with diameters of 31 ^m and 19 ^m by comparison of the characteristics obtained before and after bonding. Also estimation of energy-to-data ratio was performed for a 19 ^m microdisk lasers after bonding at 13 °C and 20 °C.
1. Cornet C., Lfeger Y., Robert C., Integrated Lasers on Silicon, ISTE Press — Elsevier, 2016.
2. Kryzhanovskaya N. V. et al., Microdisk injection lasers for the 1.27-^m spectral range, Semiconductors. 50 (3) (2016) 390-393.
3. Moiseev E., Kryzhanovskaya N., Maximov M., Zubov F., Nadtochiy A., Kulagina M., et al., Highly efficient injection microdisk lasers based on quantum well-dots, Optics Letters. 43 (19) (2018) 4554-4557.
4. Zhukov A. E., Kryzhanovskaya N. V., Moiseev E. I., Nadtochiy A. M., Dragunova A. S., Maximov M. V., et al., Impact of self-heating and elevated temperature on performance of quantum dot microdisk lasers, IEEE Journal of Quantum Electronics. 56 (5) (2020) 1-8.
5. Joyce W. B., Dixon, R. W., Thermal resistance of heterostructure lasers, Journal of Applied Physics. 46 (2) (1975) 855-862.
6. Kryzhanovskaya N., Moiseev E., Nadtochiy A., Maximov M., Dragunova A., Fetisova M., et al., Monolithic and hybrid integration of InAs/GaAs quantum dot microdisk lasers on silicon, In Integrated Optics: Design, Devices, Systems and Applications. VI 1775 (2021) 117750P.
7. Zubov F., Maximov M., Moiseev E., Vorobyev A., Mozharov A., Berdnikov Y., et al., Improved performance of InGaAs/GaAs microdisk lasers epi-side down bonded onto a silicon board, Optics Letters. 46 (16) (2021) 3853-3856.
8. Moser P., Hofmann W., Wolf P., Lott J. A., Larisch G., Payusov A., et al., 81 fJ/bit energy-to-data ratio of 850 nm vertical-cavity surface-emitting lasers for optical interconnects, Applied Physics Letters. 98 (23) (2011) 231106.
REFERENCES
THE AUTHORS
DRAGUNOVA Anna S.
ORCID: 0000-0002-0181-0262
MINTAIROV Sergey A.
[email protected] ORCID: 0000-0002-6176-6291
KRYZHANOVSKAYA Natalia V.
[email protected] ORCID: 0000-0002-4945-9803
NADTOCHIY Alexey M.
[email protected] ORCID: 0000-0003-0982-907X
MOISEEV Eduard I.
ORCID: 0000-0003-3686-935X
GUSEVA Yulia A.
[email protected] ORCID: 0000-0002-7035-482X
ZUBOV Fedor I.
KULAGINA Marina M.
ORCID: 0000-0002-3926-8675
ORCID: 0000-0002-8721-185X
KALYUZHNYY Nikolay A.
[email protected] ORCID: 0000-0001-8443-4663
ZHUKOV Alexey E.
[email protected] ORCID: 0000-0002-4579-0718
Received 13.07.2022. Approved after reviewing 14.07.2022. Accepted 15.07.2022.
© Peter the Great St. Petersburg Polytechnic University, 2022
