The Growth and Optoelectronic Properties of In(Ga)As Quantum Ring and its Application in Infrared Photodetectors

• Main Authors: Jong-Horng Dai, 戴忠弘
• Other Authors: Si-Chen Lee
• Format: Others
• Language: en_US
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/33200796551417076107

博士 === 臺灣大學 === 電子工程學研究所 === 96 === The growth mechanisms of the In(Ga)As quantum rings (QRs) and its precursors InAs quantum dots (QDs) were investigated by using atomic force microscopy (AFM), transmission electron microscope (TEM) and photoluminescence (PL). The substrate cooling methods on the morphology of surface QDs were studied, it was discovered that turning off power immediately after growth could avoid variation in surface morphology of QDs significantly. Ripening and In adatoms migration results in size redistribution during the QD annealing time, and the elastic relaxation of QDs was also observed. Strain induced In adatoms aggregation to 3D InAs island by annealing was found when the InAs coverage is below critical thickness. The QDIPs with various size QDs were fabricated and analyzed. The detection peak of QDIPs was tailorable from 5 to 10 um. It is because the QD size influences the absorption band of QDIPs. During the growth of QR, dewetting phenomenon occurs when the GaAs capped on InAs QDs are annealed, the thickness of thin GaAs capped layer was sequentially increased to study the strain effect on the transformation of small to large InAs islands to ring structure, and the relationship between the optical properties and morphology was observed. The aspect ratio of InAs QD will affect the shape of In(Ga)As QR. Finally the In(Ga)As/GaAs quantum ring infrared photodetector are analyzed in detail. By employed a thin GaAs layer to tailor the cutoff wavelength of QRIP to 100 um, the terahertz QRIP was fabricated successfully. The mechanism responsible for the far infrared response was explained.