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Ellis AR, Duffy DA, Marko IP, Acharya S, Du W, Yu SQ, Sweeney SJ. Challenges for room temperature operation of electrically pumped GeSn lasers. Sci Rep 2024; 14:10318. [PMID: 38705884 DOI: 10.1038/s41598-024-60686-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2024] [Accepted: 04/26/2024] [Indexed: 05/07/2024] Open
Abstract
Recent demonstrations of room-temperature lasing in optically pumped GeSn show promise for future CMOS compatible lasers for Si-photonics applications. However, challenges remain for electrically pumped devices. Investigation of the processes that limit device performance is therefore vital in aiding the production of future commercial devices. In this work, a combined experimental and modelling approach is utilised to explore the dominant loss processes in current devices. By manipulating the band structure of functioning devices using high hydrostatic pressure techniques at low temperature, the dominant carrier recombination pathways are identified. This reveals that 93± 5% of the threshold current is attributable to defect-related recombination at a temperature, T = 85 K. Furthermore, carrier occupation of L-valley states (carrier leakage) is responsible for 1.1± 0.3% of the threshold current, but this sharply increases to 50% with a decrease of just 30 meV in the L- Γ separation energy. This indicates that thermal broadening of a similar order may reproduce these adverse effects, limiting device performance at higher temperatures. Temperature dependent calculations show that carrier occupation of indirect valley L-states strongly affects the transparency carrier density and is therefore very sensitive to the Sn composition, leading to an effective operational temperature range for given Sn compositions and strain values. Recommendations for future device designs are proposed based on band structure and growth optimisations.
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Affiliation(s)
- A R Ellis
- James Watt School of Engineering, University of Glasgow, Glasgow, G12 8LT, UK
| | - D A Duffy
- James Watt School of Engineering, University of Glasgow, Glasgow, G12 8LT, UK
| | - I P Marko
- James Watt School of Engineering, University of Glasgow, Glasgow, G12 8LT, UK
| | - S Acharya
- Material Science and Engineering Program, University of Arkansas, Fayetteville, AR, 72701, USA
- Department of Electrical Engineering and Computer Science, University of Arkansas, Fayetteville, AR, 72701, USA
| | - W Du
- Department of Electrical Engineering and Computer Science, University of Arkansas, Fayetteville, AR, 72701, USA
- Institute for Nanoscience and Engineering, University of Arkansas, Fayetteville, AR, 72701, USA
| | - S Q- Yu
- Department of Electrical Engineering and Computer Science, University of Arkansas, Fayetteville, AR, 72701, USA
- Institute for Nanoscience and Engineering, University of Arkansas, Fayetteville, AR, 72701, USA
| | - S J Sweeney
- James Watt School of Engineering, University of Glasgow, Glasgow, G12 8LT, UK.
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2
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Recent Progress on Ge/SiGe Quantum Well Optical Modulators, Detectors, and Emitters for Optical Interconnects. PHOTONICS 2019. [DOI: 10.3390/photonics6010024] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Germanium/Silicon-Germanium (Ge/SiGe) multiple quantum wells receive great attention for the realization of Si-based optical modulators, photodetectors, and light emitters for short distance optical interconnects on Si chips. Ge quantum wells incorporated between SiGe barriers, allowing a strong electro-absorption mechanism of the quantum-confined Stark effect (QCSE) within telecommunication wavelengths. In this review, we respectively discuss the current state of knowledge and progress of developing optical modulators, photodetectors, and emitters based on Ge/SiGe quantum wells. Key performance parameters, including extinction ratio, optical loss, swing bias voltages, and electric fields, and modulation bandwidth for optical modulators, dark currents, and optical responsivities for photodetectors, and emission characteristics of the structures will be presented.
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3
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Qi Z, Sun H, Luo M, Jung Y, Nam D. Strained germanium nanowire optoelectronic devices for photonic-integrated circuits. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2018; 30:334004. [PMID: 29968583 DOI: 10.1088/1361-648x/aad0c0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Strained germanium nanowires have recently become an important material of choice for silicon-compatible optoelectronic devices. While the indirect bandgap nature of germanium had long been problematic both in light absorption and emission, recent successful demonstrations of bandstructure engineering by elastic strain have opened up the possibility of achieving direct bandgap in germanium, paving the way towards the realization of various high-performance optical devices integrated on a silicon platform. In particular, the latest demonstration of a low-threshold optically pumped laser in a highly strained germanium nanowire is expected to vitalize the field of silicon photonics further. Here, we review recent advances and challenges in strained germanium nanowires for optoelectronic applications such as photodetectors and lasers. We firstly introduce the theoretical foundation behind strained germanium nanowire optoelectronics. And several practical approaches that have been proposed to apply tensile strain in germanium nanowires are further discussed. Then we address the latest progress in the developments of strained germanium nanowire optoelectronic devices. Finally, we discuss the implications of these experimental achievements and the future outlook in this promising research field.
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Affiliation(s)
- Zhipeng Qi
- School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798 Singapore, Singapore
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4
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Vakarin V, Chaisakul P, Frigerio J, Ballabio A, Le Roux X, Coudevylle JR, Bouville D, Perez-Galacho D, Vivien L, Isella G, Marris-Morini D. Sharp bends and Mach-Zehnder interferometer based on Ge-rich-SiGe waveguides on SiGe graded buffer. OPTICS EXPRESS 2015; 23:30821-30826. [PMID: 26698715 DOI: 10.1364/oe.23.030821] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The integration of germanium (Ge)-rich active devices in photonic integrated circuits is challenging due to the lattice mismatch between silicon (Si) and Ge. A new Ge-rich silicon-germanium (SiGe) waveguide on graded buffer was investigated as a platform for integrated photonic circuits. At a wavelength of 1550 nm, low loss bends with radii as low as 12 µm and Multimode Interferometer beam splitter based on Ge-rich SiGe waveguide on graded buffer were designed, fabricated and characterized. A Mach Zehnder interferometer exhibiting a contrast of more than 10 dB has been demonstrated.
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Frigerio J, Vakarin V, Chaisakul P, Ferretto M, Chrastina D, Le Roux X, Vivien L, Isella G, Marris-Morini D. Giant electro-optic effect in Ge/SiGe coupled quantum wells. Sci Rep 2015; 5:15398. [PMID: 26477947 PMCID: PMC4609994 DOI: 10.1038/srep15398] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2015] [Accepted: 09/22/2015] [Indexed: 11/29/2022] Open
Abstract
Silicon-based photonics is now considered as the photonic platform for the next generation of on-chip communications. However, the development of compact and low power consumption optical modulators is still challenging. Here we report a giant electro-optic effect in Ge/SiGe coupled quantum wells. This promising effect is based on an anomalous quantum-confined Stark effect due to the separate confinement of electrons and holes in the Ge/SiGe coupled quantum wells. This phenomenon can be exploited to strongly enhance optical modulator performance with respect to the standard approaches developed so far in silicon photonics. We have measured a refractive index variation up to 2.3 × 10−3 under a bias voltage of 1.5 V, with an associated modulation efficiency VπLπ of 0.046 V cm. This demonstration paves the way for the development of efficient and high-speed phase modulators based on the Ge/SiGe material system.
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Affiliation(s)
- Jacopo Frigerio
- L-NESS, Dipartimento di Fisica, Politecnico di Milano, Polo di Como, Via Anzani 42, I 22100 Como, Italy
| | - Vladyslav Vakarin
- Institut d'Electronique Fondamentale, Univ. Paris-Sud, CNRS UMR 8622, Bât. 220, 91405 Orsay Cedex, France
| | - Papichaya Chaisakul
- Institut d'Electronique Fondamentale, Univ. Paris-Sud, CNRS UMR 8622, Bât. 220, 91405 Orsay Cedex, France
| | - Marcello Ferretto
- L-NESS, Dipartimento di Fisica, Politecnico di Milano, Polo di Como, Via Anzani 42, I 22100 Como, Italy
| | - Daniel Chrastina
- L-NESS, Dipartimento di Fisica, Politecnico di Milano, Polo di Como, Via Anzani 42, I 22100 Como, Italy
| | - Xavier Le Roux
- Institut d'Electronique Fondamentale, Univ. Paris-Sud, CNRS UMR 8622, Bât. 220, 91405 Orsay Cedex, France
| | - Laurent Vivien
- Institut d'Electronique Fondamentale, Univ. Paris-Sud, CNRS UMR 8622, Bât. 220, 91405 Orsay Cedex, France
| | - Giovanni Isella
- L-NESS, Dipartimento di Fisica, Politecnico di Milano, Polo di Como, Via Anzani 42, I 22100 Como, Italy
| | - Delphine Marris-Morini
- Institut d'Electronique Fondamentale, Univ. Paris-Sud, CNRS UMR 8622, Bât. 220, 91405 Orsay Cedex, France
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6
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Luo S, Wang Y, Tong X, Wang Z. Graphene-based optical modulators. NANOSCALE RESEARCH LETTERS 2015; 10:199. [PMID: 26034412 PMCID: PMC4444650 DOI: 10.1186/s11671-015-0866-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2015] [Accepted: 03/17/2015] [Indexed: 05/22/2023]
Abstract
Optical modulators (OMs) are a key device in modern optical systems. Due to its unique optical properties, graphene has been recently utilized in the fabrication of optical modulators, which promise high performance such as broadband response, high modulation speed, and high modulation depth. In this paper, the latest experimental and theoretical demonstrations of graphene optical modulators (GOMs) with different structures and functions are reviewed. Particularly, the principles of electro-optical and all-optical modulators are illustrated. Additionally, the limitation of GOMs and possible methods to improve performance and practicability are discussed. At last, graphene terahertz modulators (GTMs) are introduced.
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Affiliation(s)
- Siyuan Luo
- />Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu, 610054 People’s Republic of China
- />State Key Laboratory of Electronic Thin Film and Integrated Devices, School of Microelectronics and Solid-State Electronics, University of Electronic Science and Technology of China, Chengdu, 610054 People’s Republic of China
| | - Yanan Wang
- />Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu, 610054 People’s Republic of China
| | - Xin Tong
- />Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu, 610054 People’s Republic of China
| | - Zhiming Wang
- />Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu, 610054 People’s Republic of China
- />State Key Laboratory of Electronic Thin Film and Integrated Devices, School of Microelectronics and Solid-State Electronics, University of Electronic Science and Technology of China, Chengdu, 610054 People’s Republic of China
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7
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Littlejohns CG, Nedeljkovic M, Mallinson CF, Watts JF, Mashanovich GZ, Reed GT, Gardes FY. Next generation device grade silicon-germanium on insulator. Sci Rep 2015; 5:8288. [PMID: 25656076 PMCID: PMC4319176 DOI: 10.1038/srep08288] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2014] [Accepted: 01/12/2015] [Indexed: 11/09/2022] Open
Abstract
High quality single crystal silicon-germanium-on-insulator has the potential to facilitate the next generation of photonic and electronic devices. Using a rapid melt growth technique we engineer tailored single crystal silicon-germanium-on-insulator structures with near constant composition over large areas. The proposed structures avoid the problem of laterally graded SiGe compositions, caused by preferential Si rich solid formation, encountered in straight SiGe wires by providing radiating elements distributed along the structures. This method enables the fabrication of multiple single crystal silicon-germanium-on-insulator layers of different compositions, on the same Si wafer, using only a single deposition process and a single anneal process, simply by modifying the structural design and/or the anneal temperature. This facilitates a host of device designs, within a relatively simple growth environment, as compared to the complexities of other methods, and also offers flexibility in device designs within that growth environment.
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Affiliation(s)
- Callum G. Littlejohns
- Optoelectronics Research Centre, University of Southampton, Southampton, SO17 1BJ, UK
| | - Milos Nedeljkovic
- Optoelectronics Research Centre, University of Southampton, Southampton, SO17 1BJ, UK
| | - Christopher F. Mallinson
- The Surface Analysis Laboratory, Department of Mechanical Engineering Sciences, University of Surrey, Guildford, Surrey, GU2 7XH, UK
| | - John F. Watts
- The Surface Analysis Laboratory, Department of Mechanical Engineering Sciences, University of Surrey, Guildford, Surrey, GU2 7XH, UK
| | - Goran Z. Mashanovich
- Optoelectronics Research Centre, University of Southampton, Southampton, SO17 1BJ, UK
| | - Graham T. Reed
- Optoelectronics Research Centre, University of Southampton, Southampton, SO17 1BJ, UK
| | - Frederic Y. Gardes
- Optoelectronics Research Centre, University of Southampton, Southampton, SO17 1BJ, UK
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8
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Chaisakul P, Marris-Morini D, Rouifed MS, Frigerio J, Chrastina D, Coudevylle JR, Roux XL, Edmond S, Isella G, Vivien L. Recent progress in GeSi electro-absorption modulators. SCIENCE AND TECHNOLOGY OF ADVANCED MATERIALS 2014; 15:014601. [PMID: 27877639 PMCID: PMC5090600 DOI: 10.1088/1468-6996/15/1/014601] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2013] [Revised: 12/03/2013] [Accepted: 10/28/2013] [Indexed: 05/11/2023]
Abstract
Electro-absorption from GeSi heterostructures is receiving growing attention as a high performance optical modulator for short distance optical interconnects. Ge incorporation with Si allows strong modulation mechanism using the Franz-Keldysh effect and the quantum-confined Stark effect from bulk and quantum well structures at telecommunication wavelengths. In this review, we discuss the current state of knowledge and the on-going challenges concerning the development of high performance GeSi electro-absorption modulators. We also provide feasible future prospects concerning this research topic.
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Affiliation(s)
- Papichaya Chaisakul
- Institut d’Electronique Fondamentale, Université Paris-Sud, CNRS UMR 8622, Bât. 220, F-91405 Orsay Cedex, France
| | - Delphine Marris-Morini
- Institut d’Electronique Fondamentale, Université Paris-Sud, CNRS UMR 8622, Bât. 220, F-91405 Orsay Cedex, France
| | - Mohamed-Said Rouifed
- Institut d’Electronique Fondamentale, Université Paris-Sud, CNRS UMR 8622, Bât. 220, F-91405 Orsay Cedex, France
| | - Jacopo Frigerio
- L-NESS, Dipartimento di Fisica del Politecnico di Milano, Polo di Como, Via Anzani 42, I-22100 Como, Italy
| | - Daniel Chrastina
- L-NESS, Dipartimento di Fisica del Politecnico di Milano, Polo di Como, Via Anzani 42, I-22100 Como, Italy
| | - Jean-René Coudevylle
- Institut d’Electronique Fondamentale, Université Paris-Sud, CNRS UMR 8622, Bât. 220, F-91405 Orsay Cedex, France
| | - Xavier Le Roux
- Institut d’Electronique Fondamentale, Université Paris-Sud, CNRS UMR 8622, Bât. 220, F-91405 Orsay Cedex, France
| | - Samson Edmond
- Institut d’Electronique Fondamentale, Université Paris-Sud, CNRS UMR 8622, Bât. 220, F-91405 Orsay Cedex, France
| | - Giovanni Isella
- L-NESS, Dipartimento di Fisica del Politecnico di Milano, Polo di Como, Via Anzani 42, I-22100 Como, Italy
| | - Laurent Vivien
- Institut d’Electronique Fondamentale, Université Paris-Sud, CNRS UMR 8622, Bât. 220, F-91405 Orsay Cedex, France
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Streshinsky M, Ding R, Liu Y, Novack A, Yang Y, Ma Y, Tu X, Chee EKS, Lim AEJ, Lo PGQ, Baehr-Jones T, Hochberg M. Low power 50 Gb/s silicon traveling wave Mach-Zehnder modulator near 1300 nm. OPTICS EXPRESS 2013; 21:30350-30357. [PMID: 24514613 DOI: 10.1364/oe.21.030350] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The wavelength band near 1300 nm is attractive for many telecommunications applications, yet there are few results in silicon that demonstrate high-speed modulation in this band. We present the first silicon modulator to operate at 50 Gbps near 1300 nm. We demonstrate an open eye at this speed using a differential 1.5 V(pp) signal at 0 V reverse bias, achieving an energy efficiency of 450 fJ/bit.
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Rouifed MS, Chaisakul P, Marris-Morini D, Frigerio J, Isella G, Chrastina D, Edmond S, Le Roux X, Coudevylle JR, Vivien L. Quantum-confined Stark effect at 1.3 μm in Ge/Si(0.35)Ge(0.65) quantum-well structure. OPTICS LETTERS 2012; 37:3960-3962. [PMID: 23027245 DOI: 10.1364/ol.37.003960] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Room-temperature quantum-confined Stark effect in a Ge/SiGe quantum-well structure is reported at the wavelength of 1.3 μm. The operating wavelength is tuned by the use of strain engineering. Low-energy plasma-enhanced chemical vapor deposition is used to grow 20 periods of strain-compensated quantum wells (8 nm Ge well and 12 nm Si(0.35)Ge(0.65) barrier) on Si(0.21)Ge(0.79) virtual substrate. The fraction of light absorbed per well allows for a strong modulation around 1.3 μm. The half-width at half-maximum of the excitonic peak of only 12 meV allows for a discussion on physical mechanisms limiting the performances of such devices.
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Affiliation(s)
- Mohamed Said Rouifed
- Institut d’Electronique Fondamentale, University Paris-Sud, CNRS UMR 8622, Bât. 220, 91405 Orsay Cedex, France
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11
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Chaisakul P, Marris-Morini D, Rouifed MS, Isella G, Chrastina D, Frigerio J, Le Roux X, Edmond S, Coudevylle JR, Vivien L. 23 GHz Ge/SiGe multiple quantum well electro-absorption modulator. OPTICS EXPRESS 2012; 20:3219-3224. [PMID: 22330559 DOI: 10.1364/oe.20.003219] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We report on high speed operation of a Ge/SiGe multiple quantum well (MQW) electro-absorption modulator in a waveguide configuration. 23 GHz bandwidth is experimentally demonstrated from a 3 µm wide and 90 µm long Ge/SiGe MQW waveguide. The modulator exhibits a high extinction ratio of more than 10 dB over a wide spectral range. Moreover with a swing voltage of 1 V between 3 and 4 V, an extinction ratio as high as 9 dB can be obtained with a corresponding estimated energy consumption of 108 fJ per bit. This demonstrates the potentiality of Ge/SiGe MQWs as a building block of silicon compatible photonic integrated circuits for short distance energy efficient optical interconnections.
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Affiliation(s)
- Papichaya Chaisakul
- Institut d'Electronique Fondamentale, Univ. Paris-Sud, CNRS UMR 8622, Bât. 220, 91405 Orsay Cedex, France.
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