Cryo-FIB machining of group III-V semiconductors suppresses surface nanodroplets

Under ion beam radiation, surface defects in forms of nanodroplet are randomly formed on group III-V semiconductors’ surfaces. This work demonstrates the effectiveness of cryo-FIB on suppressing surface nanodroplets formation. Using GaAs as a representative, it was found that the surface nanodroplets derived from a phase transition process of the arsenide atoms. The redundant gallium atoms will then accumulate and eventually form surface nanodroplets. Cryo-FIB at 80 K can effetely suppress this phase transition process, leading to a defect free surface finish. The effectiveness of cryo-FIB on other group III–V semiconductors including InP and InAs are also successfully demonstrated.