Ultra-High Responsivity Ultraviolet Phototransistor Enabled by Ferroelectric Gating Enhancement Based on an AlGaN\/GaN HEMT

The development of high-performance ultraviolet (UV) photodetectors is often constrained by a fundamental trade-off between responsivity, response speed, and power consumption, limiting their overall performance. Here, we demonstrate a device paradigm that effectively addresses this challenge by integrating a Bi3.25La0.75Ti3O12 (BLT) ferroelectric gate dielectric with an AlGaN\/GaN high-electron-mobility transistor (HEMT). The device architecture leverages a non-volatile polarization field of the ferroelectric material in combination with an external electric field to co-modulate the two-dimensional electron gas (2DEG) channel, offering a unique mechanism for fine-tuning the device\u2019s optoelectronic performance. Benefiting from this ferroelectric gating enhancement operation, the BLT-gated phototransistor exhibits outstanding and well-balanced optoelectronic performance, including an ultra-high responsivity of 9.42 \u00d7 105 A\/W and a specific detectivity of 7.37 \u00d7 1015 Jones. Additionally, it shows fast rise and fall times of 0.38 s and 2.84 s, respectively, and can detect weak UV light at 360 nm with an illumination intensity as low as 8 \u03bcW\/cm2. This study presents a novel approach for electrically tuning the responsivity via ferroelectric poling, revealing a promising pathway to realize high-performance UV phototransistors. These findings pave the way for future advancements in the design of UV photodetectors, offering balanced characteristics that can be applied in a wide range of practical optoelectronic applications.