Epitaxial and non-epitaxial large area GaSb-based thermophotovoltaic (TPV) cells

InGaAsSb and GaSb thermophotovoltaic cells were grown lattice-matched to GaSb substrates epitaxially by the Molecular Beam Epitaxy (MBE) method and fabricated non-epitaxially using ion-implantation. TPV cells with 1 × 1 cm dimensions were fabricated. External quantum efficiencies and device characteristics including open circuit voltage, short circuit current density, ideality factor and reverse saturation current density of the TPVs were measured and compared. For the quaternary MBE-grown InGaAsSb, obtaining high V_oc was challenging due to the low shunt resistance caused by growth defects in the relatively thick epitaxial design. However, this TPV demonstrated promising fundamental device parameters since the lowest ideality factor and reverse saturation current density were observed compared to the others. The MBE-grown GaSb TPV structures had an order of magnitude thinner epitaxy and improved shunt resistance. The implanted GaSb TPVs exhibited similar performance to the MBE TPVs indicating that implant-induced damage was not a limiting factor.