Doping Optimization in Zn-Diffused GaSb Thermophotovoltaic Cells to Increase the Quantum Efficiency in the Long Wave Range

The GaSb cells are commonly fabricated using Zn diffusion into n-GaSb substrates. The doping of GaSb cells for both base and emitter regions is optimized for increasing the quantum efficiency (QE) in the long wave range, which will enhance the cell performance in thermophotovoltaic systems. Selection of lightly Te-doped n-GaSb substrates is an effective method. The surface recombination velocity (S) has a direct impact on the emitter doping. The optimal diffusion depth increases with the decreasing of S value. The QE in the long wave range will increase with the deepening of diffusion depth if the S is kept at a low value. The GaSb cells with different junction depths were fabricated using Zn diffusion and sulfur passivation, the cell with a deep junction has the larger QE in the long wave range, which is consistent with our simulation results.