Key factors that predominantly affact electrical and mechanical properties of ultrananpcrystalline diamond films

2022 Fiscal Year Final Research Report

• Project/Area Number: 19H02436
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 26020:Inorganic materials and properties-related
• Research Institution: Kyushu University
• Principal Investigator: Yoshitake Tsuyoshi 九州大学, 総合理工学研究院, 教授 (40284541)
• Project Period (FY): 2019-04-01 – 2023-03-31
• Keywords: ナノダイヤモンド / ダイヤモンド / 同軸型アークプラズマ堆積法 / 物理気相成長法 / 硬質被膜 / オーミック電極 / 硬度 / 耐酸腐食性

Outline of Final Research Achievements

Physical properties specific to nanodiamond (ND) films were investigated and the following results were obtained. (1) Hardness of 85 GPa was achieved by applying a negative voltage. (2) We applied near-field Raman spectroscopy to ND films for the first time and demonstrated that Raman scattering light from ND crystal grains can be detected. (3) The conductive ND film was applied to n-type single crystal diamond, and it was demonstrated that the contact resistance was about one order of magnitude smaller than that of conventional Ti-based electrodes and that the interfacial potential was clearly lowered. (4) The acid corrosion resistance was examined by immersing the ND film in boiling mixed acid; while the Ti-based electrode peeled off immediately after the first session, the ND film remained below the initial contact resistance of the Ti-based electrode for 300 hours, demonstrating that the ND film has extremely high acid corrosion resistance.

Free Research Field

応用物理

Academic Significance and Societal Importance of the Research Achievements

同軸型アークプラズマ堆積法でナノダイヤモンド（NCD）膜の成長に唯一成功している。CVD法では結晶サイズを小さくするのが難しいのに対して我々の方法では容易である。数ナノサイズのNCD結晶がアモルファスカーボン（a-C）マトリックス中の存在していることは，化学結合構造の視点からすれば，四面体構造で規則的に配列した部分(NCD結晶)と結合角度がそろっていない部分(a-C)とが混在した状態，すなわち化学結合がナノスケールで変調された状態となっており，バルクとバルクの粒界のように異質なものの境界ではない。無数に内在する粒界の効果を解明することは学術的に極めて意義深い。