The Opto-electronic Properties of Quantum Dot and Quantum Ring Infrared Photodetector
Date Issued
2006
Date
2006
Author(s)
Lin, Yi-Lung
DOI
en-US
Abstract
A quantum dot infrared photodetector (QDIP) with smaller dot height of InAs quantum dots (QDs) is found exhibiting unusual polarization dependence in spectral responses. Due to smaller dot height, every QD in this QDIP averagely shares larger vertical electric field, which creates very large band-bending on the vertical-confined electron band-diagram. Under this large band-bending, the transition probability of electrons from ground to conduction band under s-polarized light increases and this causes larger spectral response of s-polarized light. Besides, by increasing the GaAs spacer thickness, the dark current of QDIP can be reduced and thus improving background limited performance (BLIP) temperature. In addition, the InGaAs quantum rings (QRs) are formed by partially capping GaAs on 2.5 ML InAs QDs and then annealing. Compared with 2.5 ML InAs QD structure, PL peak blue-shift is observed for the QR structure. This phenomenon is attributed to a larger bandgap of the InGaAs material and a smaller QR rim height. Finally, infrared photodetectors employ InGaAs QR structure (QRIPs) are successfully fabricated, and their characteristics are completely investigated.
Subjects
量子點
量子環
紅外線偵測器
quantum dot
quantum ring
infrared photodetector
Type
thesis
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