Tianfei Zhu

Fabrication of diamond microlenses by chemical reflow method

We introduce a chemical reflow method to fabricate diamond microlenses. First, photoresist pillars developed by photolithography are reflowed in organic solvent vapor atmosphere at 20 °C to form spherical segment patterns on diamond substrate. The effects of chemical solvent type and reflow time on photoresist pattern profiles are investigated. Second, via dry etching, diamond microlenses are fabricated by transferring the spherical segment pattern into substrate. Furthermore, these diamond microlenses demonstrate low numerical aperture, well-controllable curvature, and good imaging performance with projecting experiment.

Investigation of the occupancy ratio dependence for microlens arrays on diamond

Diamond microlens arrays with a high occupancy ratio were fabricated by an improved thermal reflow method. Our resultes show that the occupancy ratio of a photoresist mask could be improved with optimizing the reflow temperature, time and photoresist thickness during the reflow process. The fabricated microlens arrays exhibited a uniform arrangement and good optical performance.

Ohmic contact between iridium film and hydrogen-terminated single crystal diamond

Investigation of ohmic contact between iridium (Ir) film and hydrogen-terminated single crystal diamond has been carried out with annealing temperature from 300 to 600 °C in argon (Ar) and hydrogen ambient. Electrodes were deposited on hydrogen-terminated single crystal diamond by electron beam evaporation technique, and specific contact resistivity has been measured by transmission line model. The interface between Ir film and hydrogen-terminated single crystal diamond was characterized by transmission electron microscopy and energy dispersive X-ray spectroscopy. Theoretical calculation value of barrier height between Ir film and hydrogen-terminated single crystal diamond was around −1.1 eV. All results indicate that an excellent ohmic contact could be formed between Ir film and hydrogen-terminated single diamond.