This paper presents micro-scale piezoelectric energy harvester (PEH) that utilizes elastic diaphragm. The circular diaphragm with radius of 500 μm has three stacked layers. The 0.3 μm thick base layer/bottom electrode is made of either cubic silicon carbide on silicon (3C-SiC-on-Si) or silicon (Si). The 0.25 μm thick Aluminum Nitride (AlN) and 0.05 μm thick Molybdenum (Mo) act as piezoelectric layer and top electrode, respectively. Using Finite Element Method (FEM), 3C-SiC- and Si-based PEH structures are simulated and compared. The former generates power of 33 μW, which is 60% higher than the latter at the input acceleration of 2.25 m/s 2 , resistive load of 4 KΩ, and at room temperature. In addition, 3C-SiC-based PEH shows better performances at higher input acceleration and larger operating temperature. The results indicate potential applications of 3C-SiC-based PEH to power devices and sensors that need to operate at extreme environments.