Rooftop high concentration photovoltaic system is an attractive alternative to silicon panels in applications where high
efficiency is imperative for limited roof space. Due to the in-panel integrated 2-axis tracking structure, limited heat
dissipation makes it a significant challenge to keep solar cells cool. Finite element analysis modeling is carried out by
taking into consideration of conductive, convective, and radiative mechanisms. Dominant thermal path is identified. We
will show that, with improved designs, solar cell temperature can be reduced by more than 20C. Experimental results are
used to verify the model and to improve thermal design.
We demonstrate that GaAs/AlGaAs multiple-quantum-well (MQW) structures grown by atmospheric pressure metalorganic vapor phase epitaxy have state-of-the-art structural, optical, and electrical properties. The 50-well MQW structures, with well thicknesses ranging from 14 to 90 angstroms, were analyzed by atomic resolution transmission electron microscopy, photoluminescence, and deep-level transient spectroscopy with the aid of a theoretical model for the eigenstates of the MQWs. It is shown that the MQW structures have a layer-to-layer thickness uniformity, interface roughness, and heterojunction abruptness of only one monolayer. A selectively doped MQW structure shows an infrared absorption efficiency of 15% at a wavelength of 11 micrometers .