Monolayer films of semiconducting metal dichalcogenides, methods of making same, and uses of same

Abstract

Metal-chalcogenide films disposed on a substrate comprising at least one monolayer (e.g., 1 to 10 monolayers) of a metal-chalcogenide. The films can be continuous (e.g., structurally and/or electrically continuous) over 80% or greater of the substrate that is covered by the film. The films can be made by methods based on low metal precursor concentration relative to the concentration of chalcogenide precursor. The methods can be carried out at low water concentration. The films can be used in devices (e.g., electrical devices and electronic devices).

1 . A metal-chalcogenide film disposed on a substrate, the film comprising a monolayer of a metal-chalcogenide. 
     
     
         2 . The metal-chalcogenide film of  claim 1 , wherein the metal is Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Nb, Mo, W, or a combination thereof. 
     
     
         3 . The metal-chalcogenide film of  claim 1 , wherein the chalcogenide is sulfide, selenide, telluride, or a combination thereof. 
     
     
         4 . The metal-chalcogenide film of  claim 1 , wherein the film comprises 2 to 10 monolayers of a metal chalcogenide. 
     
     
         5 . The metal-chalcogenide film of  claim 1 , wherein the film is structurally and electrically continuous. 
     
     
         6 . The metal-chalcogenide film of  claim 1 , wherein the film is continuous over 95% or greater of the substrate that is covered by the film. 
     
     
         7 . The metal-chalcogenide film of  claim 1 , wherein the substrate is a fiber. 
     
     
         8 . The metal-chalcogenide film of  claim 1 , wherein the substrate is silicon, silicon with a silicon oxide layer or silicon dioxide layer disposed on at least a portion of a surface of the silicon, quartz, fused silica, mica, silicon nitride, boron nitride, alumina, or hafnia. 
     
     
         9 . A method of making a metal-chalcogenide film on a substrate, the film comprising 1 to 10 monolayers of the metal-chalcogenide comprising:
 contacting a metal precursor, a chalcogenide precursor, a reducing gas, and a substrate in a reactor such that the metal-chalcogenide film is formed,   wherein the metal precursor and the metal chalcogenide precursor are each present in a gas phase and the metal precursor is present at a pressure of 1×10 −2  Torr or less and the chalcogenide precursor is present at a pressure of 1×10 −1  Torr or less.   
     
     
         10 . The method of  claim 9 , wherein the contacting is carried out in the presence of a desiccant. 
     
     
         11 . The method of  claim 9 , wherein the contacting is carried out at a water concentration of less than 1×10 −2  Torr. 
     
     
         12 . The method of  claim 9 , wherein the metal precursor has a concentration lower than a concentration of the chalcogenide precursor. 
     
     
         13 . The method of  claim 9 , wherein partial pressures of the metal precursor and the chalcogenide precursor are controlled such that grains of a first monolayer are connected laterally until the first monolayer is formed across about 80% or greater of the substrate covered by the film. 
     
     
         14 . The method of  claim 12 , further comprising forming a second monolayer on the first monolayer after the first monolayer is formed on about 80% or greater of the substrate covered by the film. 
     
     
         15 . The method of  claim 13 , wherein the second monolayer is formed on the first monolayer after the first monolayer is formed on about 95% or greater of the substrate covered by the film. 
     
     
         16 . A device comprising a metal-chalcogenide film of  claim 1 . 
     
     
         17 . The device of  claim 16 , wherein the device is an electronic device. 
     
     
         18 . The device of  claim 17 , wherein the device is a laser, a photo-diode, an optical modulator, a piezoelectric device, a memory device, or a thin film transistor. 
     
     
         19 . The device of  claim 17 , wherein the device is a transistor, P—N junction, logic circuit, or analog circuit. 
     
     
         20 . The device of  claim 16 , wherein the device is an optical fiber.