Study on quantum structure infrared photodetector

Abstract

We show that the QSIP introduced modulated barrier had the characteristics of reducing dark current, increasing the responsivity and detectivity. QWIP shows the absorption of long wavelength infrared absorption. Responsivity of proposed QWIP is twice larger than that of standard QWIP. This difference is originated built in electric field in proposed modulated barrier QWIP. Detectiviy is one order larger than that of standard QWIP. This result comes from the dark current reduction structure. In long wavelength range, the operating temperature of QDIP is disappointed. The photocurrent spectroscopy is only shown in cryogenic temperature. This is because that we have not any results of structure dependency of QDIPs. Many aspects of QDIP are not studied yet. In this thesis, the absorption photocurrents of QDIP were observed from 6㎛ to 12㎛ and study the QDIP characteristics according to the doping methods. Measured photocurrents are originated the intersubband transition in InAs quantum dots. The Δλλ is 0.38 indicating that the intersubband transition is most likely bound to continuum state. The highest temperature observing the photocurrent $T_opt$ of KSMB017 and KSMB019 is 210K and 170K, respectively. This result shows the possibility of QDIPs detecting wavelength range of 8~12㎛ at higher temperature than cryogenic temperature. On the view of the limit operating temperature, QDIP is superior to QWIP. The difference of QD quality is one of the major factors to decide the $T_opt$. The quality of QDs varies severely according to doping methods. From results, we conclude that doping on the dots for high temperature operation, uniform doping in the dot for high responsivity is effective methods, respectively. We can expect that QDIP, which combine the modulated barrier structure and QD, will be operated at near room temperature.