Methods and technologies / Characterization and measurements | Research Center for Electronic and Optical Materials

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Methods and technologies
Characterization and measurements

The technologies used at this center can be broadly divided into synthesis/manufacturing technology and evaluation analysis technology.
This page focuses specifically on evaluation and measurement. Please see 【another page 】for Synthesis and processing methods.

There are also various ways to evaluate the obtained materials. Methods for investigating crystal and molecular structures, methods for evaluating electrical properties, methods for evaluating optical properties, and spectroscopic analysis for investigating electronic structures and lattice vibrations are also used. In addition, chemical evaluations such as catalytic properties and adsorption properties, as well as methods for investigating mechanical properties such as heat resistance and strength, are also used.

We also have equipment available for use by outside organizations. If you are interested, please inquire.

【Synthesis and processing】 page

Here, techniques for strctural analysis in this center will be introduced.

Scanning electron microscopy

We perform a variety of analyzes by combining scanning electron microscopes with various equipment such as spectrometers.

Evaluation of shape and defect structure using cathodoluminescence and electron beam induced current

Group in charge
Semiconductor Defect Design Group
CHEN, Jun

CL of Mg-implanted GaN. Top: 10μm SEM comparing uniform areas to dislocation spots. Bottom: 3D model of beveled layers.

Transmission electron microscopy

Transmission electron microscopy is used for various structural evaluations such as nano-sized structures and crystal defects.

Three TEM images. Top: GaAs/InAs layers. Bottom left: InAs on Si with dislocations. Bottom right: alternating WSe2/MoSe2 layers on GaAs with models.

Probe microscopes

Atomic force microscopy (AFM) is used to evaluate nano-sized surface.

AFM of semiconductor. Parallel diagonal stripes show atomic steps just one layer high. Controlled smooth surface. Droplet epitaxy. Top: Droplet formation & crystallization. Bottom: AFM of GaAs/InAs QDs & Qdashes (50-200nm). Shape control.

X-ray diffraction

It is used not only to determine crystal structure, but also to evaluate various structures such as thin film thickness and particle size.

Hybrid crystal simulations. Three panels show carbon and nitrogen networks. Bottom right: electron density with red and yellow contours around atoms.

Electron diffraction

We utilize various electron diffraction techniques such as transmission electron microscopy, RHEED, and LEED to identify crystal structures and surface structures.

By analyzing the emission direction of photoelectrons observed using X-ray photoelectron spectroscopy or ultraviolet photoelectron spectroscopy (photoelectron diffraction method), it is also possible to identify the atomic arrangement on the top-most surface and sub-surface

Group in charge
Nano Electronics Device Materials Group
YAMASHITA, Yoshiyuki

Group in chargeSemiconductor Epitaxial Structures Group
OHTAKE, AkihiroEquipment List

Photoelectron holography. Left: Atomic image. Right: Crystal models of Si-doped κ-Ga2O3, identifying Pentahedral site as stable.

We will introduce state analysis and composition analysis at this center.

Electron spectroscopy

In particular, we utilize photoelectron spectroscopy, including hard X-ray photoelectron spectroscopy, to evaluate the chemical composition and electronic structure of substances and materials.

Hard x-ray photoelectron spectroscopy

Group in charge
Electro-ceramics group
UEDA, Shigenori

HAXPES. Left: Non-total reflection for bulk probe. Right: Total reflection at a grazing angle for interface probe.

Evaluation of crystal defect states

Development of evaluation device: Photothermal deflection spectroscopy

Group in charge
Electro-ceramics Group
SUMIYA, Masatomo

GaN-HEMT research. Center: Cross-section. Around: MOCVD growth system photo & graphs of device, material & interface.

Evaluation using isotope tracer

Group in charge
Electro-ceramics group

Arrhenius plot of 18O in La2O3. Diffusion coefficient (cm2/s) decreases linearly from 10^-9 to 10^-12 as 1000/T rises from 10 to 15.

cathodoluminescence

Group in charge
Semiconductor Defect Design Group
CHEN, Jun

Bevel polishing. Small angles (<10°) expand nm-scale layers to μm-widths, increasing thickness resolution by 20 times.

We would like to introduce the property evaluation techniques at this center.

Installation of physical property evaluation method

We are developing and implementing property evaluation equipment necessary for material development, such as new measurement equipment that captures quantum phenomena.

Development of equipment for quantum optical measurements

Group in charge
Quantum Photonics Group
KURODA, Takashi

Quantum optics. Left: 3 graphs (7, 25, 80 nW) showing a sharp dip at 0ns, proving single-photon emission. Right: Optical setup.

ODMR, opticaly detected magnetic resonance

Group in charge
Semiconductor Defect Design Group
TERAJI, TokuyukiWATANABE, Kenji

Optical setup. Bright green laser beam passes through lenses on a breadboard, focusing on a sample for measurement.

Application of data science

We are proceeding with efforts to automate and make our equipment autonomous, with the aim of speeding up substance searches, avoiding missing data and human-related variations, and creating libraries for data utilization.

Development of automatic measurement system

Group in charge
Nano Electronics Device Materials Group
YAGYU, Shinjiro

Power law analysis. Left: Algorithm flowchart. Center: y=a(x-b)^c+d. Right: Power law curve linearized into a line starting at b.

Building a combinatorial smart lab system

Group in charge
Nano Electronics Device Materials Group
NAGATA, Takahiro

AI material development. Top: Cycle of design, synthesis & analysis. Bottom: BaTiO3 with <5% dielectric change (RT-400°C).

Introducing calculations and analysis at this center.

Analysis program development

We are developing programs necessary for evaluator analysis of material properties.

Impedance analysis program

Group in charge
Optical Ceramics Group
KOBAYASHI, Kiyoshi

Igor Pro for impedance analysis. Windows show Nyquist plots & relaxation time distribution. Control panel on right.

Automatic spectrum analysis program

Group in charge
Nano Electronics Device Materials Group
YAGYU, Shinjiro

Power law analysis. Left: Algorithm flowchart. Center: y=a(x-b)^c+d. Right: Power law curve linearized into a line starting at b.

Theory construction

Search for unique nanophotonics functions

Group in charge
Quantum Photonics Group
OCHIAI, Tetsuyuki

Potential on a sphere. 3D model (purple to yellow). Graph shows sharp changes at ±1, indicating surface electrical response.

Mathematical material theory

Group in charge
Semiconductor Defect Design Group
INOUE, Junichi

Material ID by light. Left: Polarized reflection. Right: Normal Insulator shows zero signal. Topological Insulator shows non-zero wavy signal.

Molecular/crystal simulation

In order to gain a deep understanding of materials, we conduct electronic state calculations based on quantum mechanics and atomic arrangement simulations based on them.

Consideration of natural minerals, nanosheets, etc

Group in charge
Environmental Circulation Composite Materials Group
SUEHARA, Shigeru

Nanomaterials. (a) Mica ion-water reaction. (b) Atomic structure & Dirac-cone energy band of siliborophene. (c) Ion penetration.

Search for semiconductors and dielectrics

Group in charge
Electro-ceramics group
OHASHI, Naoki

Hybrid crystal simulations. Three panels show carbon and nitrogen networks. Bottom right: electron density with red and yellow contours around atoms.
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