Aluminum nitride belongs to the third generation semiconductor material, which has the characteristics of high band-gap width, high thermal conductivity, high electron drift rate and high chemical stability. Because of its good physical properties, it has broad application prospects in high temperature, high frequency, high power devices and deep ultraviolet optoelectronic devices.
The common method for preparing aluminum nitride single crystal is physical vapor transfer method. In specific experiments, if the induction furnace is used to grow aluminum nitride single crystals, then the tantalum crucible and tantalum sheet are usually used as a crucible combination for crystal growth. Due to the high temperature used in the crystallization of aluminum nitride, the raw material of aluminum nitride will decompose into gaseous components, and the crucible of pure tantalum material will be deformed at high temperature, and the reaction with the gaseous components of aluminum nitride raw material will affect the result of crystal growth. Therefore, the tantalum crucible must be carbonized before crystal growth, so that the tantalum material will become a more stable tantalum carbide material. The common carbonization process is to put tantalum sheets into graphite powder, into the graphite crucible, and then carbonize at high temperature in the induction heating furnace. Due to the uneven thickness of graphite powder, the surface of tantalum sheets after carbonization will be uneven, which will affect the long crystal and make them useful.
The preparation method of tantalum carbide sheet belongs to the technical field of tantalum carbide material preparation. The technical problem to be solved by the invention is the problem of material surface flatness. The silicon nitride wedge is placed vertically against the inner wall of the graphite heater, and 1 silicon nitride wafer is placed between the 3 wedges and placed on the inner bottom surface of the graphite heater, and then 1 graphite powder wafer and 1 tantalum wafer are placed on the silicon nitride wafer in sequence, and then 1 graphite powder wafer and 1 tantalum wafer are placed above the tantalum wafer. In this order, a total of 6 graphite powder disks and 5 tantalum disks are placed, and then 1 silicon nitride disk is placed. After tightening the cover of the graphite heater, the graphite heater is put into the induction heating furnace as a whole. After vacuuming, the temperature is raised to 1800℃ within 4 hours, and then protective gas is filled into the furnace to make the furnace pressure reach 750Torr, and the heat is kept for 1 hour. After that, the furnace temperature is raised to 2100℃ for reaction. The invention is used for growing tantalum carbide sheets.
