In this paper, the optical and electrical characteristics of ultra-thin GaAs solar cell with front-surface pyramid array are investigated systematically. The results show that the cell with pyramid array could significantly improve the photon absorption efficiency due to synergistic effects of antireflection and diffraction compared with reference solar cells with single and double anti-reflective coating (ARC), and the maximal integrated quantum efficiency of 0.88 is obtained for pyramid cells, much higher than that of 0.75 and 0.71 for double and single ARC solar cells, respectively. Electric simulation demonstrates the total recombination rate of solar cell with pyramid array is higher than that of reference solar cells due to higher carrier concentration. The radiative recombination dominated in the base and emitter region, while the SRH recombination becomes the primary recombination mechanism in the space charge region, both which are much higher than Auger recombination. Surface recombination has little impact on the photovoltaic performance due to the presence of wide bandgap window layer. For pyramid cell, the J_sc,V_oc,η of 22.65mA/cm2, 1.120V and 21.84% are obtained when considering photon recycling effect, respectively, are higher than those of 19.52mA/cm2, 1.106V and 18.72% for double ARC solar cell, and those of 18.32mA/cm2, 1.106V and 17.60% for single ARC solar cell.

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