A combination study of conductivity and contact potential in low-field-emission

2019-10-28 18:17:22

potential field emission conducting microscopy

责任者: Li Zhang;Sakai, T.;Sakuma, N.;Ono, T.;Nakayama, K. 单位: Adv. Discrete Semicond. Technol. Lab., Toshiba Corp., Kawasaki, Japan 来源出处: New Diamond and Frontier Carbon Technology(New Diam. Front. Carbon Technol. (Japan)),1999//,9(1):53-61 摘要: Simultaneous measurements of surface topography of and nanoscale conductivity/potential distributions in low-field-emission carbon films were performed by conductive scanning probe microscopy (SPM). The films were produced by bias-enhanced nucleation (BEN) hot filament (HF) chemical vapor deposition (CVD). A turn-on field of as low as 1 V/μm was obtained for field-emission measurements. Simultaneous topography-current maps were obtained by bias-applied conductive atomic force microscopy (AFM) in the contact mode and showed that highly conducting sites and dielectric regions of the micro and/or nanometer order coexisted. Furthermore, in situ I-V characteristics of both regions showed that the conducting sites have a metallic ohmic property, whereas the dielectric regions have a degenerated Schottky property, which represents a semiconductor band structure. Contact potential differences (CPD) were measured as surface potential in the AC mode by Kelvin probe force microscopy (KFM). Both conductivity and contact potential (VCPD) images of one and the same area were obtained, which made it possible to evaluate the work function of the conducting sites. It is shown that the conducting sites have a work function of about 5.0 eV, which most likely indicates the graphite phase. It is revealed that randomly distributed conducting channels play an important role in the low-field-emission process. It is also suggested that simultaneous measurements of topography and conductivity/contact potential and the combination of the two are effective methods for investigating nanostructural surfaces 关键词: atomic force microscopy;carbon;contact potential;CVD coatings;electrical conductivity;electron field emission;nanostructured materials;scanning probe microscopy;surface potential;surface topography;work function;combined conductivity/contact potential/topography study;low-field-emission films;C;conductive scanning probe microscopy;surface topography;SPM;bias-enhanced nucleation hot filament chemical vapor deposition;BEN HF CVD;turn-on field;field-emission measurements;bias-applied conductive AFM;atomic force microscopy;contact mode;highly conducting sites;dielectric regions;in situ I-V characteristics;metallic ohmic property;degenerated Schottky property;semiconductor band structure;surface potential;AC mode;Kelvin probe force microscopy;KFM;work function;graphite phase;randomly distributed conducting channels;nanostructured surfaces