The University of Tokyo · Physics and Astronomy
Professor Jinkwan Kwoen's research lab specializes in the epitaxial growth and integration of III-V semiconductor materials, particularly InAs/GaAs quantum dot lasers, on silicon and III-V substrates. The lab focuses on advancing monolithic integration of high-performance photonic devices for silicon photonics, emphasizing CMOS-compatible, all-MBE growth processes to eliminate foreign buffer layers and patterning. Key research directions include optimizing nucleation layers to suppress defects such as anti-phase domains, enabling high-temperature continuous-wave operation, and developing efficient, low-threshold lasers for telecommunication bands (O, C/L, and E-band).
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Directly grown III-V quantum dot (QD) laser on on-axis Si (001) is a good candidate for achieving monolithically integrated Si photonics light source. Nowadays, laser structures containing high quality InAs / GaAs QD are generally grown by molecular beam epitaxy (MBE). However, the buffer layer between the on-axis Si (001) substrate and the laser structure are usually grown by metal-organic chemical vapor deposition (MOCVD). In this paper, we demonstrate all MBE grown high-quality InAs/GaAs QD l
Laser devices for silicon photonics are expected to be implemented in an integrated environment to complement CMOS devices. For this reason, quantum dot (QD) lasers with excellent thermal properties have been considered as strong candidates for Si photonics light sources. The direct growth of QD lasers on Si (001) on-axis substrates has been garnering attention owing to the possibility of monolithic integration on a CMOS-compatible wafer. In this paper, we report on the high-temperature (over 10
Reflection high-energy electron diffraction (RHEED) has wide application because it allows in situ observation of the sample surface behavior during molecular beam epitaxy growth. In particular, the RHEED pattern has been used as a milestone for growth condition calibration because it dynamically changes depending on the sample temperature, material supply rate, and supply ratio. However, RHEED pattern analysis depends on the accumulated know-how of the operator and has a time limitation; thus,
Abstract The direct growth of a III–V compound semiconductor on Si(001) is an unsolved problem for monolithically integrated photonic devices on the Si platform. Here, we report the growth of a high-quality GaAs layer on on-axis Si(001) substrates by MBE. A single domain GaAs layer was grown on top of a AlGaAs nucleation layer on a Si(001) substrate. By optimizing the Al content of the nucleation layer, anti-phase domains were self-eliminated at the GaAs layer. This result represents a key step
With the development of dry fiber over the past two decades, the E-band has become a new telecommunication wavelength. However, owing to material constraints, an effective high-performance semiconductor light source has not yet been realized. InAs quantum dot (QD) lasers on GaAs substrates are in the spotlight as O-band light sources because of their excellent thermal properties and high efficiency. The introduction of a very thick InGaAs metamorphic buffer layer is essential for realizing an E-
Abstract This study investigates the development of InAs quantum dot (QD) lasers on a InP(001) substrate, utilizing only III‐arsenide layers. This approach avoids the issues associated with the use of phosphorus compounds, which are evident in the crystal growth of conventional C/L‐band QD lasers, making the manufacturing process safer, simpler, and more cost‐effective. The threshold current density of the fabricated QD laser was 633 A/cm 2 , which is the lowest value for QD lasers in the 1.6‐µm
Abstract InAs quantum dots (QDs) are receiving attention as next‐generation E‐band light source that offers high‐temperature operation and temperature insensitive operation. However, high‐density crystal defects occur at the interface between the InGaAs buffer layer and GaAs, resulting in reduced device performance and shortened lifetime. Here, E‐band QD lasers are demonstrated on InGaAs buffer layer, which suppressed the spread of dislocation by introducing a high‐temperature annealing and a st
Abstract The reflection high-energy electron diffraction (RHEED) method is widely used for the in situ observation of molecular beam epitaxy (MBE). This is because the RHEED pattern dynamically changes according to the growth conditions, such as surface temperature and material supply. However, to date, the RHEED pattern has been categorized and recognized based on the experience of the researcher. In this study, we investigated the classification of RHEED pattern datasets without using labeling
Abstract We present the growth of InAs quantum dots (QD) embedded in GaAs nanowires (NW) on silicon and demonstrate clear single photon emission. Sharp excitonic emission (linewidth of 162 μeV) and the generation of single photons (g (2) (0) = 0.18) was observed by low temperature photoluminescence measurements, suggesting a high optical quality which can be attributed to the high crystal quality of the QD structure. It is believed that the crystal quality is high due to the Stranski‐Krastanov (
This study investigates the emission wavelength control of InAs quantum dots (QDs) grown on InP substrates using molecular beam epitaxy (MBE). By utilizing InAlGaAs capping layers with varying indium compositions, the emission wavelengths were tuned across the S, C, L, and U bands, making them applicable for optical communication. The use of lower indium content layers effectively reduced indium interdiffusion during the annealing process, allowing precise emission wavelength control and strain
The growth of InAs on a GaAs (001) substrate follows the Stranski–Krastanov (S–K) growth mode. Initially, the stress due to the lattice constant difference is small, resulting in two-dimensional growth. However, as the thickness of the growth layer increases, this stress accumulates, and upon reaching a critical film thickness, the growth transitions to three-dimensional, facilitating stress relaxation. Strain changes during crystal growth can be observed through variations in substrate curvatur
ABSTRACT This study demonstrates the growth of InAs quantum dots (QDs) on InP substrates using an all group III‐arsenide approach in molecular beam epitaxy (MBE) with a low‐indium‐composition InAlGaAs partial capping layer. Real‐time curvature measurements confirm effective strain compensation during multilayer QD growth, enabling precise control of emission wavelength and structural stability. The fabricated lasers exhibited successful operation at a telecommunication C‐band.
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