Effect of Electron Injection and Temperature on the Gas Sensitivity of Diamond-Graphite Film Structures to Water Vapor

Gas sensors based on wide-gap metal-oxide materials (including tin dioxide) make it possible to detect a wide range of organic and inorganic gases. However, the number of materials used to obtain them is limited, and they are environmentally hazardous. For the development of “green” semiconductor technologies, the creation of new materials and structures with gas-sensitive properties, as well as competitive methods for their production, is of considerable interest from both fundamental and applied points of view. The work investigates the possibilities of using diamond-graphite film structures obtained in the plasma of a microwave gas discharge of ethanol vapor as gas-sensitive materials. The patterns of the effect of the electron-injection voltage and the air temperature and humidity on the current–voltage characteristics and surface resistivity of diamond-graphite film structures are studied. It is shown that the patterns can be described using the theory of space-charge-limited currents in noncrystalline structures with capture traps. The existence of a band with an increased density of localized electron states with an energy of about 0.032 eV at the edge of the allowed band of the electronic structure of the material used, which determines the nature of the dependences of the surface resistivity of the sensor structure on the parameters of detection of the gas environment, is established. The high efficiency of using diamond-graphite film structures for detecting water vapor is shown in the form of a more than threefold decrease in their surface resistivity compared to the absence of water vapor in the atmosphere.