| SnO2is a direct wide band gap (3.6eV) semiconductor material, which has a high exciton binding energy (-130meV). However, light emission from band to band recombination in SnO2is impossible due to its dipole-forbidden nature. In this context, the electroluminescence (EL) taking advantage of the defects states of SnO2has received research interest. In this thesis, the SnO2/P+-Si heterostructured LED devices have been prepared and the low bias/voltage driven EL has been realized. The primarily results achieved in this thesis are summarized as follows.(1) The EL from the SnO2/p+-Si heterostructured LED devices with the SnO2films annealed at different post-annealing temperatures has been investigated. It is found that the EL from the SnO2/p+-Si heterostructured device is much stronger with the SnO2film annealed at higher annealing temperature, which exists a higher desity of defect states. However, the EL threshold voltage of such device is higher due to that a thicker SiOx insulating layer is formed between the SnO2and/P+-Si substrate.(2) The EL from the Sn2/P+-Si heterostructured device is enhanced dramatically by adding a capped-TiO2layer on the SnO2film. The densification of SnO2film as a result of the TiO2capping which suppresses the violation of SnO2is responsible for reducing the non-radiative centers. Moreover, the large refractive index of TiO2is favorable for extraction of emitted light from SnO2film. Such two effects of TiO2capping contribute to the aforementioned enhanced EL.(3) The Al-doped ZnO (AZO) transparent conductive oxide films have been deposited under different conditions of RF-sputtering. It is shown that the AZO films has the best electrical performace when the substrate temperature is between250-300℃. Moreover, the conductivity of the AZO films deposited with lower working pressures are improved. The SnO2/p+-Si heterostructured device exhibits enhanced EL by replacing the ITO electrode with AZO one. |
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