Panda Kalpataru, Sankaran Kamatchi Jothiramalingam, Panigrahi Binaya Kumar, Tai Nyan-Hwa, Lin I-Nan
Graduate School of Engineering, Osaka University , 2-1 Yamada-Oka, 565-0871 Suita, Osaka, Japan.
ACS Appl Mater Interfaces. 2014 Jun 11;6(11):8531-41. doi: 10.1021/am501398s. Epub 2014 May 27.
The effect of hydrogen plasma treatment on the electrical conductivity and electron field emission (EFE) properties for diamond nanowire (DNW) films were systematically investigated. The DNW films were deposited on silicon substrate by N2-based microwave plasma-enhanced chemical vapor deposition process. Transmission electron microscopy depicted that DNW films mainly consist of wirelike diamond nanocrystals encased in a nanographitic sheath, which formed conduction channels for efficient electron transport and hence lead to excellent electrical conductivity and EFE properties for these films. Hydrogen plasma treatment initially enhanced the electrical conductivity and EFE properties of DNW films and then degraded with an increase in treatment time. Scanning tunneling spectroscopy in current imaging tunneling spectroscopy mode clearly shows significant increase in local emission sites in 10 min hydrogen plasma treated diamond nanowire (DNW10) films as compared to the pristine films that is ascribed to the formation of graphitic phase around the DNWs due to the hydrogen plasma treatment process. The degradation in EFE properties of extended (15 min) hydrogen plasma-treated DNW films was explained by the removal of nanographitic phase surrounding the DNWs. The EFE process of DNW10 films can be turned on at a low field of 4.2 V/μm and achieved a high EFE current density of 5.1 mA/cm(2) at an applied field of 8.5 V/μm. Moreover, DNW10 films with high electrical conductivity of 216 (Ω cm)(-1) overwhelm that of other kinds of UNCD films and will create a remarkable impact to diamond-based electronics.
系统研究了氢等离子体处理对金刚石纳米线（DNW）薄膜的电导率和电子场发射（EFE）特性的影响。通过基于N2的微波等离子体增强化学气相沉积工艺，将DNW薄膜沉积在硅衬底上。透射电子显微镜显示，DNW薄膜主要由包裹在纳米石墨鞘中的线状金刚石纳米晶体组成，这些纳米晶体形成了有效的电子传输导电通道，从而使这些薄膜具有优异的电导率和EFE特性。氢等离子体处理最初增强了DNW薄膜的电导率和EFE特性，但随后随着处理时间的增加而降低。在电流成像隧道光谱模式下的扫描隧道光谱清楚地表明，与原始薄膜相比，经过10分钟氢等离子体处理的金刚石纳米线（DNW10）薄膜中的局部发射位点显著增加，这归因于氢等离子体处理过程在DNW周围形成了石墨相。延长（15分钟）氢等离子体处理的DNW薄膜的EFE特性下降是由于DNW周围纳米石墨相的去除。DNW10薄膜的EFE过程可以在4.2 V/μm的低场下开启，并在8.5 V/μm的外加场下实现5.1 mA/cm(2)的高EFE电流密度。此外，具有216（Ω cm）(-1)高电导率的DNW10薄膜超过了其他类型的非晶金刚石（UNCD）薄膜，将对基于金刚石的电子学产生显著影响。
