The Growth and Optoelectronic Properties of InAs/AlGaAs/GaAs Quantum Dot Infrared Photodetectors
Date Issued
2005
Date
2005
Author(s)
Chen, Shen-De
DOI
en-US
Abstract
The growth mechanisms of the InAs QDs were investigated by using AFM, SEM, TEM and PL. Phase separation growth of InGaAs cap layer on InAs QDs was also observed. GaAs tends to fill up the valley between InAs QDs whereas InAs is forced to remain on the dots, which leads to longer emission wavelength. The effective quantum well model including strain was developed to calculate the energy levels inside the InAs QD and successfully interpreted the PL spectra. The stress mainly comes from the upper GaAs cap layer rather than the lower GaAs matrix. A QDIP with AlGaAs or InAlGaAs blocking layers was fabricated and analyzed. By introducing a 2 nm Al0.3Ga0.7As cap layer on 3 (2.2) ML InAs QDs, the high-performance narrow-bandwidth multicolor InAs/AlGaAs/GaAs QDIPs were successfully fabricated. The origins of the responses were explained. The negative differential conductance, temperature-dependent and TE-mode-enhanced responses were observed. The negative differential conductance is due to intervalley scatterings. The temperature-dependent response originates from the electronic mobility as a function of temperature. The enhanced TE-mode responses could be engineered by RTA and explained by the transition from the S-like ground state to the strain-induced splitting of P-like first excited states, and the RTA process changes the stress inside InAs QDs due to the bond breaking.
Subjects
量子點
紅外線偵測器
砷化銦
quantum dot
infrared photodetector
InAs
Type
thesis
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