We investigate the effect of strain on the two-dimensional electron gas (2DEG) channel in a flexible Al0.25Ga0.75N/GaN high-electron-mobility transistor (HEMT) by mechanical bending to prove the concept of active polarization engineering to create multifunctional electronic and photonic devices made of flexible group III-nitride thin films. The flexible HEMTs are fabricated by a layer-transfer process and integrated with a 150-μm-thick Cu film. The strain values are estimated from high-resolution x-ray diffraction and Raman spectroscopy in 4-cm bend-down and −4-cm bend-up test conditions. The strain-induced piezoelectric polarization can alter the charge density of the 2DEG in the channel at the AlGaN/GaN interface and thus modify the output characteristics of the flexible HEMTs. Accordingly, output characteristics show an increase in output current by 3.4% in the bend-down condition and a decrease by 4.3% in the bend-up condition. Transfer characteristics show a shift of threshold voltage, which also supports the 2DEG channel modulation during bending. Computational simulation based on the same structure confirms the same current modulation effect and threshold voltage shift. Furthermore, the electrical characteristics of the flexible HEMTs show a repeatable dependence on the strain effect, which offers potential for electro-mechanical device applications.

中文翻译：

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通过机械弯曲调制柔性 AlGaN/GaN 高电子迁移率晶体管中的二维电子气通道

我们通过机械弯曲研究应变对柔性 Al0.25Ga0.75N/GaN 高电子迁移率晶体管 (HEMT) 中二维电子气 (2DEG) 通道的影响，以证明有源极化工程的概念以创建多功能由柔性 III 族氮化物薄膜制成的电子和光子器件。柔性 HEMT 通过层转移工艺制造，并与 150 微米厚的铜膜集成。应变值是根据高分辨率 X 射线衍射和拉曼光谱在 4 厘米弯曲和 -4 厘米弯曲测试条件下估算的。应变引起的压电极化可以改变 AlGaN/GaN 界面处通道中 2DEG 的电荷密度，从而改变柔性 HEMT 的输出特性。因此，输出特性显示在弯下状态下输出电流增加 3.4%，在弯上状态下减少 4.3%。传输特性显示阈值电压的偏移，这也支持弯曲期间的 2DEG 通道调制。基于相同结构的计算仿真证实了相同的电流调制效果和阈值电压偏移。此外，柔性 HEMT 的电气特性显示出对应变效应的可重复依赖性，这为机电设备应用提供了潜力。基于相同结构的计算仿真证实了相同的电流调制效果和阈值电压偏移。此外，柔性 HEMT 的电气特性显示出对应变效应的可重复依赖性，这为机电设备应用提供了潜力。基于相同结构的计算仿真证实了相同的电流调制效果和阈值电压偏移。此外，柔性 HEMT 的电气特性显示出对应变效应的可重复依赖性，这为机电设备应用提供了潜力。