Recrystallization of an amorphized epitaxial phase-change alloy: A phoenix arising from the ashes

摘要

Epitaxial Ge_2Sb_2Te_5 films grown on Si(111) by molecular beam epitaxy were reversibly switched between crystalline and amorphous states over a large area using femtosecond laser pulses. The structural and spatial homogeneity of the as-grown epitaxial and laser-switched areas on the sample were investigated by synchrotron nanofocus high resolution x-ray diffraction. The investigation clearly demonstrated that the single crystalline metastable cubic phase of Ge_2Sb_2Te_5 is restored after switching. No polycrystalline features, not only on the average but even on the nanometer scale of the x-ray beam, were observed.