High-Performance Flexible Ultraviolet Phototransistor Based on an AlGaN/GaN Heterojunction Membrane

The AlGaN/GaN-based high electron mobility transistor (HEMT) has proven to be an excellent candidate to construct a high-performance ultraviolet photodetector. However, the previously reported AlGaN/GaN HEMT-based three-terminal photodetectors (photo-HEMT) were built on a rigid substrate, significantly restricting their potential for flexible and wearable applications. The construction of a flexible photo-HEMT using a single-crystalline AlGaN/GaN heterojunction membrane represents a significant milestone in the development of flexible phototransistors, enabling diverse applications across various domains. We have successfully released an AlGaN/GaN membrane from an AlGaN/GaN-on-insulator and transferred it onto a flexible substrate to fabricate a flexible photo-HEMT. The AlGaN/GaN-based flexible photo-HEMT exhibits excellent optoelectronic performance, with a detectivity of 2.7 × 10¹⁶ Jones at a wavelength of 360 nm. It outperforms the previously reported three-terminal flexible phototransistors. Moreover, the performance of flexible photo-HEMTs can be further improved by the strain-induced piezo-photonic effect. Compatibility with existing GaN technology will open up the doors for the commercialization of flexible optoelectronics.