| Summary: | 碩士 === 長庚大學 === 光電工程研究所 === 93 === Investigations of the physical characteristics of quantum dot infrared photodetectors(QDIPs) are presented in this thesis. First,QDIP is bound-to-bound intersubband transition in our experiment. The responsivity of temperature dependent on QDIP is discussed in the thesis. In QWIPs, it has been confirmed that the responsivity in most devices are temperature independent. In QDIPs, the responsivity increases with bias and temperature. The influences of responsivity are current gain and quantum efficiency. The gain, the same as responsivity, increases with bias and temperature. However, the temperature-dependent of quantum efficiency is more complicated, and the effects on responsivity are relatively small.
The change of dark current causes the excess carriers in QDs to change. The increasing excess carriers will decrease the capture probability, and lead to QDIP gain increased with temperature. Furthermore, the finite number of states inside QDs will affect quantum efficiency when there are more carriers in the QDs. The results are different from that of QWIPs. According to the our analysis, we can realize the optimum number of carriers in QD is 2. Details are discussed in the thesis.
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