High-density plasma sources, such as inductively coupled plasma (ICP) and electron-cyclotron-resonance (ECR) plasma, are key technologies for developing precise etching processes in ULSI devices. The disadvantages of these technologies include several types of radiation damage caused by the charge buildup or by ultraviolet (UV) and vacuum ultraviolet radiation (VUV), and X-ray photons during etching. For sub-22-nm devices, defect-free and charge-free atomic layer etching processes are indispensable. To achieve a breakthrough for these problems and achieve accurate nanoscale patterning, a high-performance neutral-beam etching system has been developed. Our group has developed a highly efficient neutral-beam source to accomplish the ultimate top-down etching for future nanoscale devices.

Although Ge electron devices have not been on our minds for a long time, Ge research has turned into quite a hot topic recently. This is due to the fact that our understanding of Ge difficulties has rapidly progressed and new technology that overcomes them is now being developed. This is in addition to the fact that Si devices face a fundamental limit for their performance. This article discusses what the real challenges in Ge technology are, how to overcome the technical hurdles, and furthermore how to remarkably improve the device properties.

Optical systems based on optical fiber devices are generally robust from external interference so that they can be applied in industrially reliable systems in various fields. In this section, we describe how fiber lasers generate femtosecond laser pulses using optical fiber as gain media and an optical path. We also represent an example of an application for a non-destructive paint multilayer measurement of automotive parts using a terahertz wave generated and detected by a femtosecond fiber laser system.

Diamonds show low resistive hopping conduction at room temperature for heavily doped films. Using this property, diamond electronic devices are being developed. By use of this property, the difficulty of having high resistivity for diamond devices, which is caused by deep donor states for n-type phosphorus doping and deep accepter states for p-type boron doping, will be overcome. There are many issues in physics related to hopping conduction as well as electronic devices using it. Although diamonds and silicon are the same indirect transition semiconductor, the electron hole recombination process in diamonds is quite different from the case of silicon. This process is very important to the understanding of diamond device physics. In this article I introduce recent progress regarding these research themes.

In this article, techniques of electro-optic (EO) sampling of terahertz (THz) waves based on non-collinear Cherenkov-phase matching are detailed. In contrast to conventional collinear phase-matching, the restrictions in choosing the EO crystal and the sampling optical wavelength for the THz EO sampling are largely alleviated with the non-collinear Cherenkov-phase matching. In addition, “heterodyne EO sampling” based on Cherenkov-phase matching is reported. In the heterodyne EO sampling, no polarization optics are required and thus the EO sampling optics are greatly simplified because the heterodyne EO sampling directly detects the intensity modulation in the sampling optical beam induced by the EO effect.

We have been developing a new microscopy technique, which enables the ultimate spatial and temporal resolution, by combining scanning tunneling microscopy (STM) with an ultrashort pulse laser technique based on the optical pump-probe method. The probing of ultrafast spin dynamics has also been realized. Spin precession was successfully observed by applying a magnetic field and an analysis of the local Lande g factor has also become possible. The present status and future development of femtosecond time-resolved STM are discussed using recently obtained results.

Quantum information processing such as quantum teleportation can be realized utilizing the quantum entanglement inherent in a solid such as photon emission and absorption. I, here, introduce our research regarding the application of quantum info-communications such as a quantum repeater utilizing a nitrogen-vacancy center in a diamond as a spin qubit.