This work aims at improving the energy harvester performance by using low-dimensional thermoelectric materials. A micro-thermoelectric generator with quantum well thermocouples is developed by state-of-the-art CMOS (Complementary metal-oxide semiconductor) process. A relaxation-time model is applied to analyze the characteristic length of silicon germanium quantum well, and a thermal model is also applied to calculate the thermocouple size for optimal performance by matching the thermal/electrical resistance. Analysis based on TSMC 0.35μm 3P3M (3-poly and 3-metal layers) BiCMOS process shows that the quantum well thermocouples (0.05 μm Si0.9Ge0.1 quantum well on 0.300 μm P-thermoleg and 0.280 μm N-thermoleg) has the best performance. that the power factor and voltage factor is 0.241 μW/cm 2K2 and 10.442 V/cm2K.