On the Crystallization of Ge₂Sb₂Te₅ Thin Films Using a Thin-Film Resistive-Heating Element for Creating Optoelectronic and Integrated-Optical Elements and Devices on Their Basis

Thin films of Ge₂Sb₂Te₅ (GST) material are characterized by a high phase-transformation rate (<50 ns) and optical contrast (~30%) between amorphous and crystalline structures. A common way to switch GST thin films between the amorphous and crystalline states is laser radiation. However, the reversible switching of large elements of a GST functional area can only be implemented in the surface scanning mode with a pulsed laser beam, which significantly increases the switching time. This paper presents a design for switching a microscale GST functional area by means of a thin-film resistive-heating element. It is found that the crystallization of a GST functional area with a size of 100 × 100 μm and thickness of 30 nm into the face-centered cubic (fcc) structure occurs when passing a single electric pulse with a duration of 200 ms and an amplitude of 2.1 V (~310 mA) through the heating element or at a voltage of 1.7 V and a current of ~220 mA in the DC measurement mode. According to computer modeling, under this electrical action, the GST area heats up to a temperature of ~218°C. The results obtained demonstrate the possibility of using the developed and manufactured structure for creating elements of nonvolatile active optical and optoelectronic devices, including information displays.