[9p-PA3-1~18] 6.2 Carbon-based thin films

▼ [9p-PA3-17] Spectroscopic study on boron-doped ultrananocrystalline diamond thin films synthesized by coaxial arc plasma: Toward the application to UV photodetector

〇Naofumi Nishikawa^1,2, Satoshi Takeichi¹, Yuki Katamune³, Koichiro Hoshino¹, Keisuke Ohdaira², Tsuyoshi Yoshitake¹ (1.Kyushu Univ., 2.JAIST, 3.Kyutech)

Keywords:ultrananocrystalline diamonds, coaxial arc plasma deposition, spectroscopy

Ultrananocrystalline diamond (UNCD) thin films are synthesized by various chemical vapor deposition (CVD) techniques in general, however we succeeded in preparations of UNCDs by the other way, named coaxial arc plasma (CAPD) deposition in 2010. Since UNCD films prepared by CAPD possess more an amorphous carbon (a-C) fraction and grain boundaries (GBs) compared to those by common CVDs, they own different physical properties. The most distinguished one is their light absorption coefficients excessing 10⁵ cm^-1 in the photon range of 3 to 6 eV, which are at least 2 orders of magnitude larger than those by CVDs. Hence UNCD films by CAPD are especially potential of the applications to UV photodiodes. While a lot of research on the UNCDs toward such applications have been accumulated for around a decade, some of them concluded hydrogen incorporation into the films were effective to enhance photovoltaic performances in these diodes. It has been technically difficult to inject more hydrogen for several years, however we solved the problem in 2018. At the conference, we deliver comprehensive studies of our lab's project, describing the most important factor in the applications of UNCD films by CAPD to photodiodes, by use of some spectroscopy.