Method for preparing alpha-phase molybdenum carbide crystals through microwave plasma enhanced chemical vapor deposition

Abstract

The invention belongs to the field of two-dimensional crystal preparation and discloses a method for preparing alpha-phase molybdenum carbide crystals through microwave plasma enhanced chemical vapor deposition. The method is characterized by comprising the steps of 1, placing cleaned silicon wafers into a cavity of a device for preparing the molybdenum carbide crystals and vacuumizing the cavity; 2, guiding hydrogen gas into the cavity, adjusting the microwave power, the hydrogen flow and the air pressure and stimulating generation of plasmas after gas inside the cavity absorbs the microwave energy; 3, covering the silicon wafers with the plasmas, heating the silicon wafers, adjusting a vacuum micrometering valve and enabling the air pressure inside the cavity to be kept within a certain range; and 4, sequentially guiding methane and molybdenum hexafluoride into the cavity after the state of the plasmas becomes stable, adjusting the gas flow and the proportion, turning off a microwave source after reaction is completed, taking out samples after the cavity is cooled and finally obtaining the alpha-phase molybdenum carbide crystals. The purity of the molybdenum carbide crystals prepared through the method is high, research on the characteristics such as the electric property and the superconductivity of the molybdenum carbide crystals is convenient, and the obtained samples have low-temperature superconductivity.

Description

technical field [0001] The invention belongs to the field of two-dimensional crystal preparation, and in particular relates to a method for preparing α-phase molybdenum carbide crystals by a microwave plasma chemical vapor deposition device. Background technique [0002] With the discovery of graphene and graphene-like two-dimensional materials, two-dimensional materials have attracted much attention due to their unique structure and composite form, and exhibit excellent properties. When the material is thinned to a certain thickness, the electronic structure will appear. The change of the energy band gap leads to the improvement of the electronic transition mode. Two-dimensional materials have a wide range of applications in electro-optical devices, catalysis, electrochemistry, photodetection, etc. Transition metal carbides (TMCs), such as molybdenum carbide (Mo 2 C) is a class of materials with special properties and applications. In the crystal structure, the combinatio...

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Problems solved by technology

[0003] It is reported that molybdenum carbide crystals will undergo superconducting transition at a temperature of 10K. However, the related research results are not the same. The main reason is that there are certain defects in the preparation method of molybdenum carbide crystals.

Most of the traditional molybdenum carbide crystal preparation methods use a mixed gas of methane and hydrogen to reduce molybdenum oxide, and the product is a powdery molybdenum carbide crystal. Due to the difficulty in controlling the reaction time and degree of reaction, the product contains graphite and amorphous carbon.

However, the presence of impurity components such as carbon-containing compounds will greatly affect the performance of molybdenum carbide

Although, the use of different carbon sources, such as dimethyl ether, butane, etc., can effectively reduce the carbon-containing impurity components in molybdenum carbide, but the agglomeration of molybdenum carbide and carbon-containing components will affect the specific surface area and Catalytic performance

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