| Summary: | 碩士 === 國立交通大學 === 電子物理系所 === 100 === The electron emission properties of the EL2 defect state with (without) illumination in 2.2-ML(monolayer) InAs self-assembled quantum dots (QDs) containing an EL2 defect state is presented. Initially, the defect state is observed at the temperature dependence capacitance-voltage (C-V) profiling, leading to the faster electron emission rate with temperature increasing. The source of the EL2 defect state is studied by deep-level transient spectroscopy (DLTS) measurements. Moreover, we calculate the concentration of the EL2 defect state, which is compared with the doping background concentration of top GaAs layer.
Under an energy illumination of 0.8 eV, the large capacitance produces, suggesting the electron emission rate of the EL2 defect state increasing. An expression of electron emission rate is dependent with the intensity of the excited light source and optical cross section. Furthermore, the electron occupancy probability is changed upon illumination. The DLTS measurement under illumination also shows the electron emission rate increasing. Finally, the electron-hole pairs produce in the QDs and defect states under illumination energy of 0.7-1.56 eV can explain the relationship between photocapacitance, photocurrent, and carrier radiative recombination. Furthermore, a simple rate equation can describe this phenomenon.
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