Crack-free interface in wafer-bonded Ge/Si by patterned grooves

Crack-free interfaces can be achieved in wafer-bonded Ge/Si by using patterned grooves. Using synchrotron radiation phase-contrast imaging and scanning electron microscopy, we observe cracking that is induced by thermal stresses in thin (hGe ⩽ 0.5hSi) Ge wafers on smooth Si substrates. Theoretical calculation shows a remarkable reduction in thermal stresses in Ge wafer bonded to grooved Si substrate. We demonstrate the fabrication of crack-free Ge/Si (hGe = 0.5hSi) structure by patterned grooves, as confirmed by an ohmic I–V characteristic across the heterojunction.