Preparation And Characterization Of Intermediate Band Semiconductor Materials CuGaSe₂:Ge

Intermediate band solar cell is a new concept solar cell with high efficiency and low cost, which can make full use of the infrared spectrum of sunlight photon energy, the theoretical limit of efficiency of these solar cells up to63.2%. Copper-based compound CuGaSe2, the band gap is very close to the ideal value of the intermediate zone of the matrix material, also has large absorption coefficient and high defect tolerance, is often used as the absorbent layer of the high efficiency thin film solar cells, it is an ideal matrix material of the intermediate band. Currently, the efficiency of the copper-based thin film solar cell has reached the maximum efficiency20.8%, but only use part of the spectral energy of sunlight, if the intermediate band is introduced in the copper-based absorbing layer, can effectively use solar spectral energy and improve the efficiency. In this dissertation, the CuGao.75Geo.25Se2(CGGS) quaternary compounds target will sputtering on soda-lime glass, after further annealing, which prepared different compositions CuGaSe2:Ge films with different substrate temperatures.The crystal structure and film surface morphology of CuGaSe2:Ge thin film are characterized by the X ray diffraction (XRD), Scanning Electron Microscopy (SEM). With the UV-visible spectrophotometer we analyzed the light absorption, reflection and transmission characteristic. The results show that:the exploit of PLD devices can prepare high crystallinity and smooth surface intermediate band semiconductor CuGaSe2:Ge thin film; the peaks film (112) of CuGaSe2:Ge becomes more stronger as the substrate temperature elevated, when the substrate temperature is500℃,(112) diffraction peak of the total crystalline phase peak intensity ratio is the maximum; with the increasing of Ge content, lattice spacing decreases, CuGaSe2:Ge intermediate semiconductor thin film with an optical band gap is reduced; the dope of group VI atom Ge in CuGaSe2, the photon energy are respectively0.89eV and0.71eV, the optical band gap is1.60eV and capable of forming the intermediate band, achieve full utilization of the energy of the sunlight spectrum and improve the conversion efficiency.