by Akira Uedono, University of Tsukuba
In the past four decades, we have witnessed quick and large growth of the semiconductor industry, and how it has driven advances in communication, energy, health care, and security. Now it becomes the indispensable technology of our society. This great success of electronic industries was attributed to continuous and aggressive downsizing of the metal–oxide– semiconductor field-effect transistors (MOSFET). Another important achievement was light emitting diodes (LED) and semiconductor lasers based on compound semiconductors, which resulted in 2014 Nobel Prize in Physics for the development of efficient blue GaN LEDs (Akasaki, Amano, and Nakamura). Here, widegap semiconductors, especially group-III nitrides, played an important role, and they are now ready to use for power electronics, which expected to give a large impact on our society again.
Although the tremendous success of semiconductor technologies has been made, the researchers always have fought against material defects such as impurities and dislocations. With our present technology, those defects seem to be under control, but the final and big obstacle is small self-point defects; vacancies and interstitials. From ’60, an anti-particle of electron, positron, was found to be trapped by vacancy-type defects, and it can provide useful information of the defects. Nowadays, positron annihilation spectroscopy is recognized as the powerful non-destructive defect detection tool which can be applied to almost all kind of materials.
In the present lectures, the recent developments and future of semiconductors technology are described. The lectures (2 hours × 4) were divided into two parts; R&D of group-III nitride- based light-emitting/power-device technology and that of Si-based technology. After their introductions, a role of point defects studied by means positron annihilation spectroscopy will be described.
Date, time and location: Lecture 1 June 20, 2019 10:15 – 11:45 Lecture 2 June 21, 2019 10:15 – 11:45 Von-Dankelmann-Platz 3 R1.04