2018 Fiscal Year Research-status Report
Thermal stability improvement of diamond logic circuits for high-temperature application
| Project/Area Number |
18K13806
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| Research Institution | National Institute for Materials Science |
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Principal Investigator |
劉 江偉 国立研究開発法人物質・材料研究機構, 機能性材料研究拠点, 独立研究者 (30732119)
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| Project Period (FY) |
2018-04-01 – 2020-03-31
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| Keywords | diamond / MOSFET / logic circuits |
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| Outline of Annual Research Achievements |
High annealing temperature operations for hydrogenated diamond (H-diamond) metal-oxide-semiconductor field-effect transistors (MOSFETs) are investigated. The SiO2 films are employed as oxide insulators for the H-diamond MOSFETs. After annealing at 500 deg. C for 60 min, although leakage current density of the SiO2/H-diamond MOS capacitor increases, good operations and distinct pinch-off characteristics are observed for the SiO2/H-diamond MOSFET with current output maximum, on/off ratio, and subthreshold swing of -2.6 mA/mm, 1.4×104, and 530 mV/dec, respectively. Stable electrical characteristics are confirmed for the annealed SiO2/H-diamond MOSFET after 35 cycles repeat measurements.
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| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
In this project, we propose to improve thermal stability of hydrogenated diamond (H-diamond) metal-oxide-semiconductor field-effect transistor (MOSFET) logic circuits for high-temperature applications. There are several reasons for poor thermal stability of diamond logic circuits, such as damage of ohmic contact, degradation of oxide insulators, and high requirements of device fabrication process at high-temperature. For first year of the project, we have improved the ohmic contact and developed a suitable oxide insulator to make the H-diamond MOSFETs operate well at annealing temperature as high as 500 deg. C for 60 min. Thus, we have achieved the FY2018's plan for this project. During FY2019, we attempt to make the H-diamond MOSFET logic circuits operate well at 500 deg. C.
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| Strategy for Future Research Activity |
After finding the best ohmic contact metal for the H-diamond channel layer and making the H-diamond MOSFETs operate well after annealing at 500 deg. C for 60 min during FY2018, we will improve the thermal stability of H-diamond MOSFET logic circuits during FY2019. New fabrication process for the H-diamond MOSFET logic circuits will be developed. On the other hand, the SiO2 will be used as the oxide insulator for the MOSFET. Electrical properties such as breakdown voltage, gain value, and current output of the H-diamond MOSFET logic circuits after annealing will be investigated. Our research target during FY 2019 is to make the H-diamond logic circuits operate well at temperature higher than 500 deg. C.
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| Causes of Carryover |
Since the price of diamond substrate purchased from EDP company is a little cheaper than that from Sumitomo company, around 31,525 JPY is left. During FY2019, I will use this budget to buy more diamond substrate.
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