The Electric Propulsion Laboratory, Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency invented and developed the microwave discharge ion engine with a clear distinction from what was done in America, Europe and Russia. This technology allowed the Hayabusa asteroid explorer to achieve a world-first round trip between Earth and an asteroid through its efficiency, durability and reliability. In parallel to the Hayabusa’s space flight, we discovered the internal phenomena of the ion source by way of a new probe technique using optical fibers, and succeeded in enhancing the thrust force. The improved ion engines are now accelerating the Hayabusa 2 asteroid explorer toward a new target. This article explains the high performance and durability of the electron cyclotron resonance microwave discharge ion source in comparison with conventional direct current discharge ion sources.

Scanning nonlinear dielectric microscopy (SNDM) can easily distinguish the dopant type (pn) and has a large dynamic range for a sensitivity from low to high concentrations, because SNDM has a quite high sensitivity to capacitance variation of the order of 10^-22F. It can be also applicable to the analysis of compound semiconductors with a much lower signal level than that from Si. We can avoid misjudgments from the 2-values function (contrast reversal) problem of the dC/dV signal. Under ultra-high-vacuum conditions, SNDM has an atomic resolution. These favorable features of SNDM originate from its significantly high sensitivity characteristics.

The basic elements of the semiconductor nanolaser are an optical cavity and a laser gain medium. Many structures, such as pillars, nanowires, photonic crystals, and disks have been investigated in order to realize optical cavities. Quantum dots are the most promising structure for a gain medium because they provide the highest gain per unit volume. In this paper we discuss the growth and optical properties of InAs/GaAs quantum dots embedded in GaAs/AlGaAs nanowires. Lasing oscillation was achieved in our nanowire-based quantum dot structures at room temperature. Moreover, a nanowire-based plasmonic quantum dot laser has also been demonstrated by transferring the nanowires onto a metal film/silicon substrate.

Ultra-high sensitivity CMOS image sensor (CIS) technologies, which can be utilized in the fields of broadcasting, surveillance, scientific measurement and industrial measurement will be explained. Using a folding-integration A-D converter, which reads signal from pixels with ultra-low noise while maintaining the dynamic range, established both the read noise that is equivalent to a single photoelectron and an 80dB (4 digits) dynamic range. Future prospects including the application of CISs that realize ultra-low noise equivalent to 0.3 electrons, will also be discussed.

A nitrided 4H-SiC/SiO₂ structure is the key component for high-performance 4H-SiC MOSFETs. We investigated this interface system using ESR/EDMR (electrically-detected ESR) spectroscopy. One of the most important results is the discovery of the “nitrogen doping effect.” For a standard nitridation condition (gate-oxide thickness = 50 nm and post oxidation anneal by NO at 1250°C for 60 min.), the doping concentration was found to be 2×10¹¹ cm^-2 or 7×10¹⁷ cm^-3. The nitrogen doping effect can explain various properties of the nitrided SiC-MOS interfaces. However, there are still unclear issues, such as the microscopic origin(s) of major interface states after the nitridation. EDMR studies revealed both shallow and deep interface states related to carbon atoms. These centers were removed by the nitridation.

Large high-purity (type IIa) diamond crystals up to 12 mm in diameter were grown by the temperature gradient method at high pressure and high temperature, using a high-purity Fe-Co solvent, a high-purity carbon source and high-crystalline-quality seed crystals. The large synthetic IIa diamond crystals are characterized by high-crystalline-quality, having very few dislocations or stacking faults. The X-ray projection topograph revealed that the crystals have no crystal defects especially in the (001) growth sectors. The high-quality diamond will be very useful for monochromators or optical elements, and also is highly promising for use in the electronics field such as in electronic devices and quantum devices.

The laser-assisted chemical vapor deposition process leads to high-speed crystal growth in ceramic coatings with preferred orientation and nanostructure formation. We have demonstrated orientation control of α-Al₂O₃ coatings, feather-like structure formation in β-Al₂TiO₅ coatings, nanodendrite formation in Al₂O₃–ZrO₂ coatings, and high-speed epitaxial growth of functional materials: BaTi₂O₅, YBa₂Cu₃O_7-δ, CeO₂ and 2H-SiC.

Optical nonlinearity allows various types of high speed control of light, while the effect is usually small. Si photonic crystal waveguides enhance the nonlinearity on a chip, thanks to a strong optical confinement and slow-light effect. In this paper, we present co-propagating/counter-propagating slow-light systems, in which two slow-light pulses propagate simultaneously and exhibit unique interactions. The enhanced nonlinearity as well as the engineered group-delay and dispersion in slow light gives unique functions such as adiabatic wavelength conversion, fast delay tuning, pulse compression and a Doppler shift.

The resistivity, conduction type, majority-carrier concentration and mobility in semiconductor wafers or epitaxial layers are essential electric properties. To obtain these properties, Hall-effect measurements are carried out. Therefore, this article plainly explains Hall-effect measurements and how to verify and analyze the measured results.