Vol.6 No.3 2014
Research paper : Development of diamond-based power devices (S. SHIKATA et al.)−157−Synthesiology - English edition Vol.6 No.3 (2013) lead, just as it happened in SiC. Since the device in this paper is already 1 A class, we are aiming for double-digit increase by reducing the defects. For patents, there are several that have been registered including the patent unique to diamonds.4 Advantage verificationQuestion and comment (Toshimi Shimizu)At the end of “1 Objective and outcome of research,” you write, “Phase 1 of R&D was conducted to verify the advantage….” For example, drug discovery starts from basic research, nonclinical trial using animals, and clinical trial in humans to see the efficacy and safety of the drug (Phase 1~3). Here, there is a giant difference between the research phases of whether the subjects of verification are animals or humans. In device research, what is the major synthesis element or technological element that separates Phase 1 research for concept verification and Phase 2 for practical device verification, as shown in Fig. 3? Is it a difference perceived by the author, or is it a generally accepted difference? Even if it is common sense to device researchers, the positioning of Phase 1 and 2 is not clear to the general readers.Answer (Shinichi Shikata)The concept verification of Phase 1 is an animal experiment in the sense that confirmation is done, for example, at 1 A class for whether the principle is realizable or not. The device development of Phase 2 is an efficacy check in humans in the sense that it is verification of 100 A class that can be actually implemented. The reliability test is Phase 3 or the safety test. After this, the phase proceeds to engineering samples and products. Although the names are different by companies, this is a common concept. I added supplementary explanation in Fig. 3.5 Performance verification of transistorQuestion and comment (Toshimi Shimizu)To aim for power device verification using the diamond semiconductor, I think the verification of not only diode but also transistor performance is essential. Recently, there was a paper published by an AIST research group about the success of verification of operating junction type field transistor for the first time. Your paper does not address the future prospect of transistor operation using the diamond semiconductor. If you are aiming for an ultimate power device, I think you must comment on the latest technological trend on the transistor development using diamond materials.Answer (Shinichi Shikata)There are mountains of trial results from way back, but unfortunately they involve only the lateral structure device that aims for high frequency, and there is no success with prototypes with vertical structure that may lead to the future 100 A class. However, as you say, there is a lack of reference to transistors in this paper, so I added some comments. I think this item must be studied with the participation of multiple organizations.