Today’s highly advanced information communication technology (ICT) is based on semiconductor nanoelectronics, but difficulties in achieving further performance improvements and their huge power consumption levels are critical issues worldwide. To overcome these problems, we are developing next-generation low-power-consumption optoelectronic devices, such as, high-mobility transistors and light-emitting devices that utilize strained germanium (Ge) thin films and Ge quantum nanodots, by employing the crystal growth and semiconductor process equipment installed in our clean room.
Si/Ge crystal growth
Control of MIS interfaces
Evaluation of interface properties
Two dimensional (2D) materials
Evaluation of optical properties
To create high-performance Ge-based electronic and optical devices, high -quality Ge thin layers possessing the crystal strain have to be formed on Si wafers. To accomplish this, we have developed Ge epitaxy and wafer transfer techniques that allow us to realize high quality strained Ge-on-Insulators on Si wafers.
have been obtained from strained Ge channel structures. Moreover, by using our atomic layer deposition (ALD) system, which is connected to the MBE chamber, we can form high-quality interfaces between gate insulators and Ge channels, and thus realize ultra high-mobility Ge channel MOSFETs.
To create semiconductor chips with ultra-low power consumption levels, optical interconnections on silicon chips are extremely important and light sources that are monolithically integrated on Si are necessary. To this end, we are researching strained-Ge and Ge quantum dot-based light emitters that can be epitaxially grown on Si. Such emitters, when combined with microcavities, such as microdisks and photonic crystals, will help us to realize highly efficient Si-based light emitters and optical interconnections.
Band engineering based on lattice strain introduction can alter structures from indirect to direct band types, thereby opening routes to the use of various applications on Si-based optical devices. Previously, we have succeeded in introducing very large lattice strains into Si/Ge based microstructures, such as Microbridges, which are fabricated by selective etching of Ge-on-Si and GOI wafers. In the future, we aim to develop novel devices with new functions by combining micro-resonant structures with MEMS devices.
We study their fundamental optical properties of transition metal dichalcogenides (TMDs) and clarify their unknown material properties in order to propose and develop novel next-generation devices.