Scanning tunnelling microscopy (STM) and current imaging tunnelling current spectroscopy (CITS) methods were performed on polycrystalline diamond films grown on silicon substrates grown by microwave ...plasma-enhanced chemical vapour deposition. Large tunnelling currents were observed at some grain boundaries and crystal surfaces with secondary grains. Following atomic force microscopy (AFM) measurements, we performed scanning probe contact current (SPCC) measurements to investigate the spatial variation of electrical resistance on the surface by using an AFM cantilever in contact mode. The conducting grain boundaries and facets were observed on both boron-doped and undoped samples. For microscale characterization of the field emission properties, we performed scanning probe field emission current (SPFEC) measurements. From the results of STM/CITS, AFM/SPCC and SPFEC, it is concluded that the specific grain boundaries and facets on polycrystalline diamonds work as initial points of electron emission and cause high field emission current through a conducting pass formed in the bulk.
Nitrogen-doped chemical vapour deposited diamond-like carbon (DLC) films were treated by reactive ion etching system under various conditions of CHF3 gas successively after pre-treatment with oxygen. ...Atomic force microscopy and Raman spectroscopy were carried out in order to characterize the surface morphology and chemical bond, respectively. Scanning tunnelling microscopy was used in order to investigate the surface state of the DLC films at the nanoscale level. Scanning probe field emission current measurement was performed in order to obtain the emission current mapping. The emission sites appeared to a great extent after the surface treatment by CHF3 gas and a clear activation effect was observed. We confirmed that the surface treatment using CHF3 gas affected not only the appearance of emission sites but also the activation process.
This paper presents a practical method of drift-diffusion device simulation for evaluating the effects of mechanical stress on n-type silicon semiconductor devices. The device simulation incorporates ...an electron mobility model for considering the effects of stress. In this paper, we focus on stress effects that are induced by applying inplane biaxial stress to the devices. Therefore, two physical phenomena that are attributed to mechanical stress are modeled in the electron mobility model, i.e., the changes in relative population and the momentum relaxation time (intervalley scattering) of electrons in conduction-band valleys. Stress-induced variations of direct-current characteristics on n-type metal-oxide-semiconductor (MOS) field-effect transistors are evaluated using a device simulation including the proposed electron mobility model. Then, the electron mobility model and the simulation method are verified by comparing with experimental results. It is demonstrated that experimental results can be reasonably estimated using this device simulation method. From discussions regarding the electron mobility model, it is suggested that the comprehensive stress sensitivity of MOS devices is larger than that of lightly doped silicon.
Field emission characteristics of nitrogen-doped diamond-like carbon (DLC) films deposited by the radio frequency plasma enhanced chemical vapor deposition (rf-PECVD) method were investigated by the ...scanning probe system specially designed for the micro-scale field emission current measurements. The structural changes in the films were examined by using Raman spectroscopy. Random and inhomogeneous distribution of electron emission sites was observed. The emission current and conductivity of the films were significantly increased with self-bias voltage. Activated electron emission characteristics were observed in all samples and showed stable electron emission. The activation of the films was directly related to emission site size. It indicated that electron emission activation possibly originated from the changes in sp
2 and sp
3 bonding ratio and/or formation of conductive channels.
