A high-conductivity high-mobility n-type diamond thin film and preparation method thereof

A high-conductivity high-mobility n-type diamond thin film, characterized in that the high conductivity high mobility n-type diamond thin film is prepared by the following method:

• (1) preparing a spin-coating solution:
• uniformly dispersing diamond powder with particle size of 3 nm-1 μm, an adhesive, and an activator in an organic solvent to obtain a spin-coating solution;
• wherein the mass ratio of diamond powder to the activator is 100:5-10;
• the volume of the organic solvent is 0.3-0.5 mL/mg based on the mass of the diamond powder;
• the volume ratio of the adhesive to the organic solvent is 1:20-40;
• and the activator is selected from one or more of cetyltrimethylammonium bromide, poly(diallyldimethylammonium chloride), glycerol epoxypropane, and octadecyldimethylbenzylammonium chloride;
• (2) spin-coating for seed crystal deposition:
• applying the spin-coating solution from step (1) onto a single-crystal silicon wafer surface through spin-coating involving 15-20 cycles, each cycle consisting of 1000 rpm for 10 s followed by 3000 rpm for 30 s;
• to obtain a silicon wafer coated with a dense seed crystal layer;
• (3) heat-treating:
• subjecting the silicon wafer coated with a dense seed layer from step (2) to heat-treatment in a tube furnace at 500-800° C. for 80-20 min under an argon-protected atmosphere, yielding a heat-treated silicon wafer;
• (4) using the heat-treated silicon wafer from step (3) as a substrate, performing hot-filament chemical vapor deposition with acetone as the carbon source and a tantalum wire as both the heat source and doping source to obtain a densely packed nanocrystalline diamond film;
• (5) annealing the densely packed nanocrystalline diamond film from step (4) at 900-1000° C. for 30 min to obtain the high-conductivity high-mobility n-type diamond thin film.