Phase transformation of Ge 1Sb 4Te 7 films induced by single femtosecond pulse

Abstract

Phase transformations of 100nm Ge 1Sb 4Te 7 films induced by single 130fs pulse at 800nm have been investigated with time-resolved microscope. With an average fluence of 30mJ/cm 2, a reflective intensity increase was observed within 1ps in 100nm as-deposited Ge 1Sb 4Te 7 films after excitation by intense femtosecond pulse, which was consistent to an electronically induced non-thermal phase transformation. XRD measurement confirmed that single femtosecond pulse could induce crystalline marks in 100nm as-deposited Ge 1Sb 4Te 7 films. Our results indicated that single femtosecond pulse could trigger both crystalline and amorphous phase in 100nm Ge 1Sb 4Te 7 films. The fluence for crystallization was higher than that for amorphization.