Instrumented nanoindentation is used in conjunction with scanning transmission electron microscopy to evaluate the mechanical resistance at the bonding interface of a 450 nm thick InP membrane bonded oxide-free to Si. Indentation using a Berkovich tip is shown to cause the planes in InP to rotate by as much as 16°. The shear stress resulting from this rotation causes the InP membrane to buckle, forming a debonded blister around the indented zone. The geometry of this blister is used to compute the surface bond energy of InP bonded oxide-free to Si. An average surface bonding energy of 585 mJ m−2 is reported.