EFFECT OF TEMPERATURE ON GAAS ALGAAS MULTIPLE-QUANTUM-WELL SOLAR-CELLS/

Al0.36Ga0.64As p-i-n solar cells with multiple quantum wells (MQW) GaA s/Al0.36Ga0.64As in the i-region have been tested at various temperatu res, ranging from -10 to 100 degrees C, and compared with conventional solar cells composed of either the quantum well material (GaAs) or th e barrier material (Al0.36Ga0.64As) alone. The dark current of the MQW cells lied between the dark currents of the conventional cells. The i ncrease of dark current with temperature was accompanied by a small re duction of the diode ideality factor and the main component of the dar k current was found to be dominated by recombination/generation proces ses. When the cells were illuminated with a halogen lamp of 198 mW cm( -2) intensity, the open-circuit voltage V-oc of the MQW cells was abov e the V-oc of the conventional cell consisting of the well material al one. The dependence of the number of wells in the i-region on the outp ut performance of the MQW cells was found to be more profound at low t emperatures than at high temperatures. All MQW cells examined in this work showed remarkable output performance with temperature. It has bee n clearly indicated, for the first time, that GaAs/Al0.36Ga0.64As MQW structures, when fully processed as solar cells, can deliver more outp ut power under intense illumination than conventional solar cells comp osed of the well material alone. (C) 1998 Elsevier Science S.A. All ri ghts reserved.