Based on density functional theory (DFT) and first-principles method, the feasibility of using 𝛽-𝐺𝑎2𝑂3 to make vacuum ultraviolet photocathode was studied. Eight Cs adsorption sites are chosen for the 𝛽-𝐺𝑎2𝑂3(100) surface. The adsorption energy, work function, energy band structure of 8 adsorption sites and the change of work function under different Cs coverage are calculated. The results show that the adsorption energy at all sites decreases significantly. It can be concluded that the 𝛽-𝐺𝑎2𝑂3(100) surface satisfies the necessary conditions for Cs/O activation. In addition, different cesium adsorption concentrations have an effect on the surface work function, and the overall trend is that it decreases at first and then increases. Finally, the properties of energy bands under different coverage are analyzed. The results show that the widely used method of cesium adsorption to reduce the work function is also suitable for 𝛽-𝐺𝑎2𝑂3 materials.
Doping is essential in the growth of bulk Ga2O3 substrates, which could help control the electrical and optical properties to meet the requirements of various types of Ga2O3-based devices. The n type β-Ga2O3 materials with dopants including Sn, Al, Si, H et al have been successfully carried out. To further improve its conductivity and optical properties, the finding of p type β-Ga2O3 becomes very crucial. This paper reviews the efforts about such an issue with experimental and theoretical methods, describes the achievements and limitations up to now and proposes the possible research methods to achieve the p type β-Ga2O3 material.
In order to verify the performance about the surface of β-Ga2O3 as potocathode, we calculate some related properties, such as surface energy, band structure, density of states and absorption coefficient. The result is that the surface energy of β-Ga2O3 (0 1 0) is larger than β-Ga2O3 (1 0 0) surface, which is beneficial to the adsorption of cesium. The UV absorption efficiency of the β-Ga2O3 (0 1 0) surface meets the requirements of the photocathode This work can be used as a theoretical reference for UV-photocathodes.
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