| Summary: | 碩士 === 國立交通大學 === 電子物理系所 === 102 === Diamond-like carbon (DLC) thin films consist of sp^2 and sp^3 bonding and they reveal an amorphous structure. The ratio and concentration of sp^2 and sp^3 bonds shall influence the physical properties of DLC thin films. In this work, by using scanning probe microscopy, we show electronic properties and growth behaviors of DLC thin films with regard to the thin-film deposition time.
Particle size and thickness of DLC thin films were observed by images of atomic force microscope (AFM), and current-image tunneling spectra (CITS) were obtained by scanning tunneling microscopy (STM) measurements. To obtain the band gap information of the DLC thin films, we derived it from the calculation of CITS curves on STM images and we divided one image into 25 portions for comparison. By fitted with Gaussian function, the peak can be obtained from the statistical distribution of the band gap on each portion of the STM images. The peak represents average band gap at the specific deposition time. We found out that, with an increase of the deposition time, the average energy gap becomes larger. This result is in agreement with that measured by X-ray photoelectron spectroscopy (XPS).
On the other hand, for the DLC thin films with deposition time of 1600 - 2400 seconds, we discovered some large areas on which the CITS spectra show mainly sp^3 bonding. The area size is about 3000 - 4000 〖nm〗^2.
|
|---|
