Yoshio Yasumori

Change in Electrical Resistance of Diamond Surface Conductive Layer due to Acid Mist

Experimentally obtained results of the change in electrical resistance of the p-type diamond surface conductive layer (PSCL) are simulated using a rate equation. According to a model that simulates the process responsible for the decrease in electrical resistance caused by acid mist containing oxonium ions (H3O+), H3O+ ions react with hydrogen atoms terminating dangling bonds on the diamond surface and cause the creation of holes in diamond films. The rate equation describing these hole creation processes is set up and time-dependent electrical resistance is simulated. The simulated results are in agreement with the experimental results.

A Possible Model for Changes in Photoluminescence Wavelength of Porous Si due to Photochemical Etching

The changes in wavelength of photoluminescence (PL) along the depth direction of porous silicon (PS) have been investigated using the well known photochemical etching (PE) treatment technique. It was found that in both thicker and thinner PS samples, there existed a range where the PL output wavelength changed significantly from longer to shorter and irregular changes in the PL wavelength were observed. These results are in contrast with the result reported previously. On the basis of the band gap widening and the enhanced radiative recombination efficiency due to quantum confinement, i.e., quantum size effect, a qualitative model to explain these behaviors was proposed.

Electrodeposition of Diamond-like Carbon Films on Silicon Substrates Using N,N-Dimethylformamid

Diamond-like carbon (DLC) films were synthesized by an electrodeposition technique on silicon (Si) substrates using liquid N,N-dimethylformamid (DMF). The electrodeposition was performed in the temperature range from 40 to 80°C and the applied voltage range from -1 kV to -5 kV. The structures of the films were characterized by Raman spectroscopy. The films with the electrical resistivity of about 1010 Ωcm can be deposited using the liquid DMF under the liquid temperature of 80°C and the applied voltage of -2 kV. Moreover, the current density has an important role in the deposition of the films.