Theoretical study on electronic and optical properties of In0.53Ga0.47As (100) β2 (2×4) surface

Abstract In x Ga 1− x As is a perfect III–V compound semiconductor for the photoemissivelayer of the infrared-extension negative electron affinity photocathode. The In x Ga 1− x As used as photoemissivelayer has a better lattice match with InP used as the substrate of the photocathode when the In component is 0.53. The electron structure, formation energy, work function and the optical properties of the In 0.53 Ga 0.47 As (1 0 0) β2 (2 × 4) surface, which are closely related with the photocathode emission properties according to the photocathode formation mechanism, are calculated and analyzed in this article. The changes including the decrease of the energy gap and the appearance of the new energy bands happen to the surface energy bands due to the reconstruction of the surface atoms. The surface work function of In 0.53 Ga 0.47 As (1 0 0) β2 (2 × 4) surface which is sensitive to the near-infrared light is 4.274 eV. It is less than that of the GaAs (1 0 0) β2 (2 × 4) surface which is sensitive to the visible light. The absorption coefficient is studied a lot among the optical properties. The results show that the surface absorption coefficient is obviously bigger than that in the In 0.53 Ga 0.47 As bulk in the low energy region. Hence the In 0.53 Ga 0.47 As (1 0 0) β2 (2 × 4) surface is benefit for the formation of the negative electron affinity photocathode, which offers effective theoretical foundation for the photocathode structure design.