InAs Quantum Disk/Wire with AlGaAs/GaAs Quantum Well Coupling Effects Applied to the Intermediate Band Solar Cell
Date Issued
2016
Date
2016
Author(s)
Ku, Yun-Cheng
Abstract
This thesis studies the optical properties of InAs quantum structure, including InAs quantum disk and quantum wire with AlGaAs/GaAs quantum well. A model based on theory of linear elasticity and k p theory is developed with the aid of finite-element method to analyze effects of quantum system band structure and absorption coefficient. Numerical results show that effects of AlGaAs/GaAs quantum well change with sizes of quantum disk. When the coupling from neighboring quantum disks is strong, effects of AlGaAs/GaAs quantum well is weak and the structure of optical and electrical properties has only slightly change. When the coupling from neighboring quantum disks is weak, the periodic potential is huge barrier for disks coupling effects in the direction of the well. This potential barrier lets elections enhance in side direction coupling. The quantum well is periodic potential for the direction of quantum wire, the potential change let continuous energy state separate intermediate band. This coupling effect is strong and absorption spectrum of intermediate band to conduction band transitions is broad. The quantum structures with intermediate band have abilities to use photons below the material band gap. The best short-circuit current of the intermediate band solar cell (IBSC) structure is 34.13 (mA/cm2) which is much great than the GaAs solar cell 15.29 (mA/cm2). Moreover, the best conversion efficiency of IBSC can be achieved to 21.64 %.
Subjects
quantum dot
quantum wire
quantum well
finite element method
intermediate band solar cell
Type
thesis
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