Gate‐Tunable Spectral Response in β‐Ga₂O₃/Te Hybrid Photogating Structure for Ultrasensitive Broadband Detection

Abstract The increasing demand for multispectral information acquisition and the complexity of application environments have sparked a growing interest in broadband detection. However, achieving a high level of responsivity across a wide response range remains a significant challenge. Herein, an ultrasensitive broadband phototransistor based on hybrid photogating (HPG) structure is demonstrated, which consisted of a quasi‐2D beta‐phase gallium oxide (β‐Ga₂O₃) nanoflake as the carrier transport channel and a tellurium (Te) nanoflake as the photogating layer. Attributed to the strong doping influence of the Te nanoflake, a low off‐state current of pA level and a high on/off current ratio of ≈10⁸ are obtained. Upon 255 nm wavelength illumination, the device exhibited an ultrahigh responsivity up to 3.82 × 10⁶ A W⁻¹ and a detectivity as high as 1.59 × 10¹⁴ Jones across a large gate voltage range. Notably, an exciting infrared response is obtained with a responsivity of 138 A W⁻¹ and a detectivity of 3.70 × 10⁹ Jones under the 1550 nm wavelength illumination, exclusively achievable when the gate voltage exceeded 4 V. Leveraging the gate‐tunable spectral response, an innovative model for secure optical communication was proposed. This work presents an efficient and feasible strategy for fabricating multifunctional optoelectronic devices.