Floating Gate Schottky Junction Solar Cells With Improved Output Power

In this article, the concept of floating gate Schottky junction (FGSJ) solar cell with improved photovoltaic properties, compared to those of the conventional Schottky junction solar cell, is proposed. The floating gate junction is electrically isolated from the current collection junction in order to prevent reduction in the barrier height at the floating gate contact from load voltage. The unaffected barrier height at the floating gate junction leads to a more effective separation of photo-generated electron-hole pairs, and therefore, a better photovoltaic response. Single junction FGSJ solar cells based on n-type GaAs with different doping concentration levels and gate contact layer materials were fabricated, and their electrical and optical properties were characterized under standard 1-sun illumination condition. The measurement results show a notable improvement in both diode-like and photovoltaic properties of FGSJ solar cells compared to those of the conventional Schottky solar cells, which includes higher short-circuit current density, open-circuit voltage, and maximum output power. This is due to a higher equivalent Schottky barrier height in FGSJ solar cells compared with nonfloating gate devices. Moreover, the proposed floating gate structure can be used in metal/n-type semiconductor Schottky junctions to eliminate the use of highly p-doped wide bandgap semiconductors in p-n junctions. Also, the simpler and more cost-effective fabrication process of the FGSJ solar cells, compared to the p-n junction solar cells, could reduce the total production cost; therefore, making them financially viable for large-scale development of high-efficiency photovoltaic panels.