Theoretical study of c-GaN/GaAs single heterojunction solar cells

In this work a theoretical study of electrical behavior for a c-GaN/GaAs heterostructure as a photovoltaic device through a two-dimensional (2D) finite element numerical simulation is presented for a first time. I-V curves and electrical parameters like short circuit current (Isc), open circuit voltage (Voc), fill factor (FF) and efficiency (η) were obtained for n-i-p and n-p heterostructures with different thicknesses and doping of the layers by modeling heterostructures with characteristics parameters of this materials previously reported. As a result, an increment on Isc was observed by extending the thickness of i-GaAs layer from 12 mA/cm² for thinner heterostructures to a maximum of ~32 mA/cm² for heterostructures with i-GaAs layer >3000 nm and a decrease in Voc and FF in the range from ~1.06 V and 0.89 for n-p heterostructures to 0.75 V and 0.7 respectively for thicker i-GaAs layers allowing estimate maximum efficiencies between 23 and 25% for n-i-p and n-p configurations, respectively. This study allows demonstrating the potential of this type of heterostructures for solar cells applications, considering the possibility of using p-doping GaAs substrates for photovoltaics based in GaN.

Keywords:
GaN/GaAs; heterostructures; TCAD modeling; I-V curves; solar cell