In this work, wafer bonding of wide bandgap semiconductors of SiC and OaN were accomplished by different surface activated bonding (SAB) methods at room temperature. For SiC wafer bonding, room temperature SiC-SiC, SiC-Si and SiC-SiO 2 bonding by three kinds of SAB methods (standard SAB, Modified SAB with Si-containing Ar-beam, and Modified SAB with Si-sputtering layer) have been investigated and compared. For GaN wafer bonding, standard SAB was applied to the direct wafer bonding of GaN-Si at room temperature and modified SAB with Si-sputtering layer was employed for the bonding of GaN-diamond at room temperature. For both of the SiC bonding and GaN bonding, the bonding mechanisms were analyzed. The results of this research indicate SAB should be a promising method for the low temperature bonding of wide bandgap semiconductors.