Modeling of InGaP/InGaAs-GaAsP/Ge multiple quantum well solar cell to improve efficiency for space applications

Abstract

Multiple quantum wells (MQWs) are incorporated in the current limiting middle subcell of standard InGaP/InGaAs/Ge multi-junction solar cell (MJSC). Considering a realistic radiation dose in geo-stationary orbits (1 MeV electron irradiation-1 × 1016 cm−2 fluence), carrier lifetime is calculated and defined in the top cell and middle subcell region. The thermionic emission and recombination lifetimes are taken into consideration while defining lifetime in the middle MQW region. The physical thickness of quantum well (QW) and quantum barrier (QB) are slightly adjusted to numerically satisfy the strain balancing condition and to achieve higher efficiency at 1-sun (AM0 spectrum). In addition to interface recombination, carrier removal effects were taken into consideration by changing the intrinsic region in the PiN middle subcell into n-type. With the nonidealities taken into consideration, the proposed device exhibits an efficiency of 32% at 1-sun AM0 radiation and a peak efficiency of 37.63% at concentrated sunlight. Trap concentration of 1 × 1017 cm−3 in top cell with 10 ns lifetime defined in the middle cell emitter, base and MQW region is obtained as threshold point beyond which the device exhibits significant degradation.