Flash-lamp-induced explosive crystallization of amorphous germanium films leaving behind periodic microstructures

► Flash lamp annealing can induce the explosive crystallization of amorphous Ge films. ► Polycrystalline Ge films formed have periodic microstructures. ► The periodic microstructure consists of two regions with different grain features. ► The velocity of explosive crystallization is estimated to be 5-7 m/s. ► This particular crystallization could occur in a variety of materials.