This paper discusses recent efforts to realize GaInAsSb/GaSb TPV cells with an internal back‐surface reflector (BSR). The cells are fabricated by wafer‐bonding GaInAsSb/GaSb device layers to GaAs substrates with a dielectric/Au reflector, removing the GaSb substrate, and subsequently processing the layers using standard photolithographic techniques. The internal BSR enhances optical absorption within the device, while the dielectric layer provides electrical isolation. This approach is compatible with monolithic integration of series‐connected TPV cells and can mitigate the requirements of filters used for front‐surface spectral control. © 2003 American Institute of Physics