Article
Optics
Peter Tillmann, Benedikt Blaesi, Sven Burger, Martin Hammerschmidt, Oliver Hoehn, Christiane Becker, Klaus Jaeger
Summary: This work presents optical simulations of III-V-on-silicon solar cells with a metal grating for improved light trapping efficiency. The study demonstrates that the period of the grating is a critical parameter affecting its performance, which can be highly controlled during manufacturing using inference lithography. The results suggest a pathway to exceed the current world record efficiency of the III-V-on-silicon solar cell technology.
Article
Nanoscience & Nanotechnology
Xin Zhang, Hui Yang, Yunyan Zhang, Huiyun Liu
Summary: This study systematically analyzes the challenges in achieving vertically-standing nanowire lasers and proposes a nanowire superlattice distributed Bragg reflector to greatly enhance the performance of the lasers.
Article
Physics, Applied
Allison N. Perna, Kevin L. Schulte, John Simon, Anna K. Braun, David R. Diercks, Corinne E. Packard, Aaron J. Ptak
Summary: This article describes a fully in situ method of fabricating light-scattering structures on III-V materials via vapor phase etching and redeposition, which generates a rough morphology. The addition of PH3 during HCl etching of Ga0.5In0.5P leads to redeposition, and the size of the redeposited features is linearly increased by HCl flow rate and time exposed to HCl-PH3. The resulting Ga-rich GaInP morphologies exhibit high broadband scattering and can enhance the short circuit current density of photovoltaic devices.
JOURNAL OF APPLIED PHYSICS
(2023)
Article
Engineering, Electrical & Electronic
Javad Rahimi, Joris Van Kerrebrouck, Bahawal Haq, Johan Bauwelinck, Gunther Roelkens, Geert Morthier
Summary: This paper demonstrates the high wall-plug efficiency and low threshold current of heterogeneously integrated III-V-on-Silicon distributed feedback (DFB) lasers. A wall plug efficiency of over 12% is achieved for a 200 μm long DFB laser diode at 25 degrees C, with up to two times 6 mW of optical power coupled into the silicon waveguide and a side-mode suppression ratio of more than 40 dB. The paper also discusses the non-return-to-zero on-off keying modulation at 20 Gb/s and the transmission over a 2 km long optical fiber.
IEEE JOURNAL OF SELECTED TOPICS IN QUANTUM ELECTRONICS
(2022)
Article
Nanoscience & Nanotechnology
Dae-Hwan Ahn, Suman Hu, Kyeol Ko, Donghee Park, Hoyoung Suh, Gyu-Tae Kim, Jae-Hoon Han, Jin-Dong Song, YeonJoo Jeong
Summary: This paper proposes a highly efficient charge trap synapse using III-V materials-based tunnel field-effect transistor (TFET), which achieves a faster synaptic update speed and lower energy consumption compared to conventional MOSFET-based synapses.
ACS APPLIED MATERIALS & INTERFACES
(2022)
Article
Engineering, Electrical & Electronic
Tao Shi, Hailing Wang, Wanhua Zheng
Summary: This article reports a hybrid integrated III-V-on-Si sampled grating distributed feedback laser, which combines an III-V gain chip with a Si-on-insulator photonic integrated circuit by flip-chip bonding. The laser operates at a single wavelength with continuous wave mode and high side mode suppression ratio. It has a low threshold and high output power.
IEEE PHOTONICS TECHNOLOGY LETTERS
(2022)
Article
Chemistry, Physical
Sulafa M. Elsiddig, Yousif Sulfab
Summary: The kinetics of the oxidation of a chromium(III) complex by N-bromosuccinimide is studied, and the oxidation products are characterized. The reaction involves two steps, with the oxidation of Cr(III) to Cr(IV) being faster and the oxidation of Cr(IV) to Cr(V) being slower. The rate of the reactions is influenced by pH, with higher pH values favoring the formation of higher oxidation states of chromium.
INTERNATIONAL JOURNAL OF CHEMICAL KINETICS
(2023)
Article
Chemistry, Physical
Sawsan B. Eltahir, Ismat H. Ali, Yousif Sulfab
Summary: The kinetics of oxidation of a chromium coordination compound in aqueous acidic solution by periodate has been investigated, revealing a reaction proceeding through two parallel pathways with different dependencies on factors such as pH and periodate concentration. The thermodynamic parameters of the processes involved were reported, and it was concluded that the reaction proceeds via a one-step two-electron transfer mechanism.
INTERNATIONAL JOURNAL OF CHEMICAL KINETICS
(2021)
Article
Engineering, Electrical & Electronic
Hoy-My Phung, Philipp Tatar-Mathes, Aaron Rogers, Patrik Rajala, Sanna Ranta, Hermann Kahle, Mircea Guina
Summary: In this study, we investigate the heat transfer capabilities and power scaling limits of membrane external-cavity surface-emitting lasers (MECSELs) by examining different heat spreaders and pumping parameters. The simulation results show that double-side cooling can significantly lower the temperature, and the thermal conductivity of the heat spreaders has a larger impact on power scaling. Additionally, pumping with a super-Gaussian beam profile and double-side pumping can further improve efficiency and temperature distribution uniformity.
IEEE JOURNAL OF QUANTUM ELECTRONICS
(2022)
Article
Nanoscience & Nanotechnology
Capucine Tong, Thomas Bidaud, Eero Koivusalo, Marcelo Rizzo Piton, Mircea Guina, Helder Vinicius Avanco Galeti, Yara Galvao Gobato, Andrea Cattoni, Teemu Hakkarainen, Stephane Collin
Summary: Cathodoluminescence mapping is utilized to investigate the electron concentration gradient of Te-doped GaAs nanowires, revealing distinct electron concentration levels and gradients in nanowires grown at different temperatures.
Article
Optics
S. C. Burd, J. -P. Penttinen, P. -Y. Hou, H. M. Knaack, S. Ranta, M. Maki, E. Kantola, M. Guina, D. H. Slichter, D. Leibfried, A. C. Wilson
Summary: This article presents two systems based on vertical-external-cavity surface-emitting lasers (VECSELs) that can generate ultraviolet laser light at 235 and 313 nm wavelengths, suitable for quantum information processing with trapped beryllium ions. Each system includes a compact, single-frequency, continuous-wave VECSEL that produces high-power near-infrared light and can be tuned over tens of nanometers. One system produces 2.4 W of power at 940 nm, which is converted to 54 mW of 235 nm light for photoionization of neutral beryllium atoms. The other system uses a gain mirror based on GaInNAs/GaAs quantum wells, extending the wavelength above 1200 nm with manageable strain in the GaAs lattice, and generates 1.6 W at 1252 nm, which is converted to 41 mW of 313 nm light for laser cooling of trapped 9Be+ ions and quantum state preparation and detection. The 313 nm system is also suitable for implementing high-fidelity quantum gates.
JOURNAL OF THE OPTICAL SOCIETY OF AMERICA B-OPTICAL PHYSICS
(2023)
Article
Engineering, Electrical & Electronic
Omer Donmez, Mustafa Aydin, Selman Mutlu, Janne Puustinen, Joonas Hilska, Mircea Guina, Ayse Erol
Summary: We present experimental and analytical results on hot electron transport in as-grown and annealed n-type modulation-doped Al0.15Ga0.85As/GaAs0.96Bi0.4 quantum well structures. The drift mobility and velocity of the annealed sample are lower due to the increased 2D electron density caused by annealing. Hot electron transport occurs in parallel mode, and inter-valley transfer dominates at higher electric fields.
MATERIALS SCIENCE IN SEMICONDUCTOR PROCESSING
(2023)
Article
Optics
Nouman Zia, Samu-pekka Ojanen, Jukka Viheriala, Eero Koivusalo, Joonas Hilska, Heidi Tuorila, Mircea Guina
Summary: This paper presents a hybrid laser that combines GaSb-based semiconductor gain chips with Si3N4 photonic integrated circuits. The low-loss features of Si3N4 waveguides are utilized to integrate a tunable Si3N4 Vernier mirror. The laser exhibits a maximum output power of 15 mW and a tuning range of about 90 nm at room temperature. The low-loss performance of various Si3N4 building blocks for photonic integrated circuits is also confirmed.
Article
Energy & Fuels
Andrea Scaccabarozzi, Stefano Vichi, Sergio Bietti, Federico Cesura, Timo Aho, Mircea Guina, Federica Cappelluti, Maurizio Acciarri, Stefano Sanguinetti
Summary: We investigate the impact of quantum dot aspect ratio on the sub-gap absorption properties of GaAs/AlGaAs quantum dot intermediate band solar cells. Using droplet epitaxy, we grow AlGaAs solar cells with GaAs quantum dots, which allows for strain-free nanostructures with lattice matched materials. By varying the dot aspect ratio, we can tune the energy levels of the intermediate band, thereby altering the sub-gap absorption spectrum and charge carrier extraction. The tradeoff between thermal and optical extraction is crucial for the proper functioning of the intermediate band solar cells, with the photonic extraction mechanism from the quantum dots becoming dominant at room temperature.
PROGRESS IN PHOTOVOLTAICS
(2023)
Article
Physics, Applied
Reuben Amedalor, Petri Karvinen, Henri Pesonen, Jari Turunen, Tapio Niemi, Subhajit Bej
Summary: This study demonstrates the coexistence of resonant modes with weak dispersion and a Q-factor of approximately 1000 in diffraction gratings, along with the modes with well-known linear dispersion. The dispersion characteristics of these modes can be adjusted by controlling the polarization of the incoming light, allowing for strong or almost flat dispersion. A semi-analytical model is introduced to explain the underlying physics of these observations, and theoretical conjecture is supported by full-wave numerical simulations and experiments. The findings presented in this study will benefit applications reliant on resonances in free-space-coupled geometries.
APPLIED PHYSICS LETTERS
(2023)
Article
Engineering, Electrical & Electronic
Philipp Tatar-Mathes, Hoy-My Phung, Aaron Rogers, Patrik Rajala, Sanna Rant, Mircea Guina, Hermann Kahle
Summary: This study presents the operation of a semiconductor membrane external-cavity surface-emitting laser (MECSEL) using a gain membrane with a non-resonant cavity design. The MECSEL delivers watt-level output power, comparable to state-of-the-art results. The research shows that the design criteria for the MECSEL gain region can be relaxed compared to designs using distributed Bragg reflectors, minimizing the impact of defective Fabry-Perot micro-cavity effects.
IEEE PHOTONICS TECHNOLOGY LETTERS
(2023)
Article
Optics
Samu-Pekka Ojanen, Jukka Viheriala, Nouman Zia, Eero Koivusalo, Joonas Hilska, Heidi Tuorila, Mircea Guina
Summary: Photonic integrated circuits fabricated using a Si3N4 waveguide platform exhibit low losses in a wide wavelength region. A high-performance integrated laser with broad wavelength tunability near a 2.6 μm wavelength region is demonstrated, based on a Si3N4 photonic integrated circuit incorporating a tunable reflector and a AlGaInAsSb/GaSb quantum-well gain element. The platform also supports low propagation loss up to 3.5 μm.
LASER & PHOTONICS REVIEWS
(2023)
Article
Optics
D. Mitten, M. Hart, S. H. Warner, J. -P. Penttinen, M. Guina, Y. Kaneda
Summary: A vertical external cavity surface emitting laser (VECSEL) has been developed for a sodium guide star application. Stable single frequency operation with 21 W of output power near 1178 nm with multiple gain elements while lasing in the TEM00 mode has been achieved. This is the first demonstration of a high power single frequency VECSEL using a twisted-mode configuration and multiple gain mirrors located at the cavity folds.
Article
Physics, Applied
Y. Q. Huang, V Polojarvi, A. Aho, R. Isoaho, T. Hakkarainen, M. Guina, I. A. Buyanova, W. M. Chen
Summary: This study demonstrates the existence of nonlinear spin response in nonmagnetic materials and showcases it in a (Ga, N)As-InAs quantum dot coupled all-semiconductor nanostructure. The observed spin nonlinearity can be conveniently tuned with an external magnetic field and potentially operates at a speed exceeding 1 GHz.
PHYSICAL REVIEW APPLIED
(2023)
Article
Optics
Samu-Pekka Ojanen, Jukka Viheriala, Nouman Zia, Eero Koivusalo, Joonas Hilska, Heidi Tuorila, Mircea Guina
Summary: A discrete, tunable photonic integrated laser is demonstrated for multiwavelength spectroscopy. The laser combines a reflective semiconductor optical amplifier with a photonic integrated circuit, allowing for switching between three distinct emission wavelengths. The design simplifies the tuning mechanism compared to other hybrid lasers.
LASER & PHOTONICS REVIEWS
(2023)
Article
Chemistry, Multidisciplinary
Tristan Smolka, Michal Rygala, Joonas Hilska, Janne Puustinen, Eero Koivusalo, Mircea Guina, Marcin Motyka
Summary: The optical properties of GaSbBi layers grown on GaSb (100) substrates with different bismuth contents were investigated. The band gaps of the materials were determined using Fourier-transform photoluminescence spectra, revealing the presence of localized states connected to bismuth clustering. Time-resolved photoluminescence measurements based on single-photon counting were used to determine the characteristic photoluminescence decay time constants, which showed an increase with increasing bismuth content and clustering effects.
Article
Energy & Fuels
Janne Puustinen, Joonas Hilska, Arto Aho, Esperanza Luna, Antti Fihlman, Mircea Guina
Summary: The development of low bandgap GaAsNBi solar cells grown using MBE is reported, and the As/Ga flux ratio is found to play an important role in controlling the solar cell performance.
SOLAR ENERGY MATERIALS AND SOLAR CELLS
(2024)
Proceedings Paper
Nanoscience & Nanotechnology
Jukka Viheriala, Topi Uusitalo, Heikki Virtanen, Behzad Namvar, Patrik Rajala, Sanna Ranta, Teemu Hakkarainen, Antti Tukiainen, Guilhem Almuneau, Mircea Guina
Summary: This paper presents the development of vertical cavity surface emitting lasers (VCSELs) operating at 4.2K for energy efficient optical links between cryogenic systems and room-temperature data storage systems. The design considerations, material models, and validation of required electro-optical-thermal models are discussed. Successful operation at mA-level injection is demonstrated.
2023 IEEE PHOTONICS SOCIETY SUMMER TOPICALS MEETING SERIES, SUM
(2023)