To gain a complete understanding of the optical switch that uses phase-change material, Ge₂Sb₂Te₅ (GST), we conducted a simulation considering various physical phenomena related to the switch, such as electrical conduction, Joule heating, heat diffusion, phase change of GST, and light propagation. It was found that the phase state (amorphous and crystalline) of the GST film can be controlled by applying an appropriate pulse voltage to the indium tin oxide (ITO) heater layer, thereby changing the transmittance of the optical switch. Calculations showed that during cooling in the amorphization process, part of the GST film was recrystallized, reducing the transmittance of the optical switch in the ON state. Moreover, the large temperature difference in the GST film during heating was caused by a substantial amount of Joule heat generated in the region distant from the GST film. This difference in distance from the heat-generating region resulted in a considerable temperature difference in the GST film. Thus, herein, we have proposed modified model structures to reduce this temperature difference in the GST film, which can recrystallize during the amorphization process. Calculation using the modified model structures revealed that increasing the thickness of the ITO heater layer, over which the GST film was not placed, can effectively reduce the temperature difference and eventually suppress recrystallization.

为了全面了解使用相变材料 Ge ₂ Sb ₂ Te ₅ (GST) 的光开关，我们进行了考虑各种因素的模拟与开关相关的物理现象，例如导电、焦耳热、热扩散、GST 的相变和光传播。研究发现，通过向氧化铟锡（ITO）加热层施加适当的脉冲电压，可以控制GST薄膜的相态（非晶态和晶态），从而改变光开关的透射率。计算表明，在非晶化过程的冷却过程中，部分GST薄膜发生再结晶，降低了光开关在ON状态下的透过率。此外，加热期间GST膜中的大温差是由远离GST膜的区域产生大量焦耳热造成的。与发热区域的距离差异导致 GST 薄膜中存在相当大的温差。因此，在此，我们提出了改进的模型结构来减少 GST 薄膜中的温差，GST 薄膜可以在非晶化过程中再结晶。使用修改后的模型结构进行计算表明，增加未放置GST薄膜的ITO加热器层的厚度可以有效减小温差并最终抑制再结晶。