METHOD OF FORMING VANADIUM DIOXIDE MICROSTRUCTURE CONTAINING METAL-SEMICONDUCTOR TRANSITION Russian patent published in 2024 - IPC C30B29/16 C01G31/02 C30B7/10 C30B30/00 H10N97/00 

FIELD: materials science; microelectronics.

SUBSTANCE: invention relates to material science and microelectronics and can be used in making transistors, microactuators, bolometers, thermochromic smart windows, modulators and switches in the terahertz range. First, a solution of the vanadyl complex is prepared by mixing organic acids and inorganic vanadium-containing precursors with constant stirring and heating to 60 °C. For example, oxalic acid and vanadium pentoxide or ammonium metavanadate are mixed in molar ratio of 2:3 or 2:1, respectively, or citric acid and vanadium pentoxide in molar ratio of 2:1. Concentration of cations (V⁴⁺) in the obtained solution of the vanadyl complex is 0.005-0.1 M. Films of VO₂(B) are then formed by hydrothermal synthesis, for which pre-cleaned substrates are placed in Teflon inserts, filled with prepared solution of vanadyl complex, additional solvents are added, inserts are placed in a stainless steel autoclave and heat treated for 4-48 hours at 160-220 °C with subsequent cooling to room temperature. Additional solvents used are ethylene glycol and water in volume ratio of 0:100 to 50:50 or ethyl alcohol and water in volume ratio of 0:100 to 50:50. Then the substrates with the VO₂(B) films deposited on them are removed from the solution, washed, dried at room temperature and treated with femtosecond laser radiation, which initiates the transition from the VO₂(B) metastable phase to the VO₂(M) stable phase, at power 0.5-10 W, frequency 75-100 kHz, focal distance 120-12,000 mm and speed of laser 1-1.8 mm/min. Substrates with surface crystallographic parameters close to VO₂(M) are used. Topological structure from VO₂, obtained by said method, has resolution of not more than 1 mcm, semiconductor-metal transition with change in conductivity by 1,000-10,000 times in temperature range of 30-80 °C and a change in throughput in range from 0 to 2 THz, which is not less than 80%.

EFFECT: method of producing said topological structure is easily scaled and simplified owing to exclusion of photolithography methods and the stage of long-term annealing under high vacuum conditions in a controlled atmosphere.

8 cl, 2 ex