In this work, we have designed a novel gas inlet structure for efficient usage of growth and doping precursors. Our previous gas injection configuration is that the gas is mixed to one pipe first, then divided into two pipes, and finally entered the chamber symmetrically above the substrate without a jet nozzle. The distance between gas inlet and substrate is about 14.75 cm. Our new design is to add a new tube in the center of the susceptor, and the distance between the new tube and substrate is about 0.5 cm. In this new design, different gas injection configurations have been planned such that the gas flow in the reactor aids the transport of reaction species toward the sample surface, expecting the utilization efficiency of the precursors being improved in this method. Experiments have shown that a high doping efficiency and fast growth could be achieved concurrently in diamond growth when methane and diborane come from this new inlet, demonstrating a successful implementation of the design to a diamond microwave plasma chemical vapor deposition system. Compared to our previous gas injection configuration, the growth rate increases by 15-fold and the boron concentration increases by ~ 10 times. COMSOL simulation has shown that surface reaction and precursor supply both have a change in determining the growth rate and doping concentration. The current results could be further applied to other dopants for solving the low doping efficiency problems in ultra-wide-band-gap semiconductor materials.

The purpose of this research was to study treatment characteristics of main odor substances, such as Trimethylamine and Acetaldehyde, by using 600 Wand 200 W microwave plasmas. Ar and air were used as plasma gases and a cylindrical SiC/Zeolite filter having several Ø 2~3 ㎜ size holes was used as a trigger to obtain a stable plasma even with a relatively low microwave power. The 600 W Ar plasma was used to destroy relatively high concentrated TMA and acetaldehyde from 500 ppm to 2200 ppm and their DREs (Destroy and Removal Ratios) were measured. The 200 W air plasma was also used to measure DREs for TMA and acetaldehyde Jowly concentrated in 4.5 odor strength. The results demonstrated that the Ar plasma produced 70% to 90% efficiency in removing odors substances. The 200 W Air plasma, which was operated at the relatively lower energy level, produced 90% or even above higher efficiency for the odorous materials. It was expected that the air plasma was effectively used to control odorous materials emitted from relatively a small size plant process.