The superior electrical characteristics of the heterojunction III-V Tunnel FET (TFET) devices can outperform current technologies in the process of energy harvesting conversion at ultra-low power supply voltage operation (sub-0.25 V). In this work, it is shown by simulations that a cross-coupled switched-capacitor topology with GaSb-InAs TFET devices present better conversion performance compared to the use of Si FinFET technology at low temperature variations (¿T < 3 ºC) when considering a thermo-electric energy harvesting source (with a = 80 mV/K). At higher ¿T, the conversion process is degraded with the increase of the transistor losses. Considering a ¿T of 1 ºC (2 ºC), one cross-coupled stage with TFET devices can achieve 74 % (69 %) of power conversion efficiency when considering an output load of 0.4 µA (6 µA). At the same conditions, the FinFET charge pump is shown inefficient.