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Nozaki, Mikito*; Ito, Joyo*; Asahara, Ryohei*; Nakazawa, Satoshi*; Ishida, Masahiro*; Ueda, Tetsuzo*; Yoshigoe, Akitaka; Hosoi, Takuji*; Shimura, Takayoshi*; Watanabe, Heiji*
Applied Physics Express, 9(10), p.105801_1 - 105801_4, 2016/10
Times Cited Count：5 Percentile：24.79(Physics, Applied)Interface reactions between Ti-based electrodes and n-type GaN epilayers were investigated by synchrotron radiation X-ray photoelectron spectroscopy. Metallic Ga and thin TiN alloys were formed at the interface by subsequently depositing Al capping layers on ultrathin Ti layers even at room temperature. By comparing results from stacked Ti/Al and single Ti electrodes, the essential role of Al capping layers serving as an oxygen-scavenging element to produce reactive Ti underlayers was demonstrated. Further growth of the metallic interlayer during annealing was observed. A strategy for achieving low-resistance ohmic contacts to n-GaN with low-thermal-budget processing is discussed.
Kitatsuji, Yoshihiro
Bunseki, 2015(6), p.239 - 244, 2015/06
Electrochemical studies of ion transfer and charge transfer at liquid/liquid interface reported between 2012 and 2014 were surveyed. They were categorized by method of measurement. The merit of the method, improvement, species of application were described. Applied research such as analyses of redox inactive species, sensitive analyses based on adsorption at the interface and developments of new functional materials had been widely carried out.
; ;
Journal of Nuclear Science and Technology, 20(7), p.603 - 610, 1983/00
Times Cited Count：4 Percentile：50.99(Nuclear Science & Technology)no abstracts in English
+C powders and compacts to UC; ; ;
Journal of Nuclear Science and Technology, 19(3), p.222 - 230, 1982/00
Times Cited Count：12 Percentile：75.26(Nuclear Science & Technology)no abstracts in English
Asahara, Ryohei*; Nozaki, Mikito*; Yamada, Takahiro*; Ito, Joyo*; Nakazawa, Satoshi*; Ishida, Masahiro*; Ueda, Tetsuzo*; Yoshigoe, Akitaka; Hosoi, Takuji*; Shimura, Takayoshi*; et al.
no journal, ,
AlGaN/GaN high electron mobility transistor (HEMT) with metal-oxide-semiconductor (MOS) gate structure has gained much attention as next-generation high frequency and high power devices. In this study, an improvement in thermal stability and interface properties of AlGaN/GaN MOS structure by using AlON gate dielectrics has been demonstrated. Synchrotron radiation photoemission spectroscopy (SR-PES) revealed that Ga and Al atoms were diffused from AlGaN into overlying AlO
layer during annealing at 800 degrees. In contrast, the spectra for AlON sample remain almost unchanged even after the annealing, indicating high thermal stability of AlON/AlGaN structure. Furthermore, the negligible hysteresis in capacitance-voltage characteristics and interface state density as low as 1.2
10
cm
eV
were obtained for AlON/AlGaN/GaN MOS capacitors.
Nozaki, Mikito*; Yoshigoe, Akitaka; Ito, Joyo*; Asahara, Ryohei*; Nakazawa, Satoshi*; Ishida, Masahiro*; Ueda, Tetsuzo*; Hosoi, Takuji*; Shimura, Takayoshi*; Watanabe, Heiji*
no journal, ,
Structural changes at Ti/GaN or Al/Ti/GaN interfaces were studied by using synchrotron radiation photoelectron spectroscopy. It was found that the Al capping layer plays an important role for oxygen diffusion barriers. The Al layer also stimulates interfacial reactions via introducing oxygen into Ti layers. We found that this reaction dramatically changes Ti/GaN interface structures.
