| Summary: | 碩士 === 臺灣大學 === 電子工程學研究所 === 98 === We study the fabrication and the properties of GaAs/GaAs0.97Sb0.02N0.01 heterjunction diodes deposited on GaAs. The energy gap of the GaAs0.97Sb0.02N0.01 layer is 1.17 eV. We found that all the forward currents are higher than the expected p/n junction diffusion current and increases as the GaAs0.97Sb0.02N0.01 layer thickness increases. In addition, the current is proportional to the perimeter instead of the area of the junction, suggesting that it originates from the recombination on the junction surface. From the Arrhenius plot of the saturation current, we found that the activation energy of the as-grown sample is close to half the energy gap of GaAs0.97Sb0.02N0.01, suggesting that the current is a defect recombination current. After thermal annealing, the activation energy increases, indicating the suppression of the surface recombination current. Coating SiN and SiN/SiO2 passivation layers on the junction surface significantly reduces both the reverse and forward currents. The passivated GaAs/ GaAs0.97Sb0.02N0.01 heterjunction shows an optimum conversion efficiency of 6.6% under 42 times of AM1.5G illumination.
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