Gate-tunable high-responsivity photodiode based on 2D ambipolar semiconductor

Abstract Electrically tunable homojunctions based on ambipolar two-dimensional materials have attracted widespread attention in the field of intelligent vision. These devices exhibit inherent switchable positive and negative photovoltaic properties that effectively mimic the behavior of human retinal cells. However, the photovoltaic responsivity of most electrically tunable homojunctions remains significantly low due to the weak light absorption, making it challenging to meet the application requirements for high-sensitivity target detection in the field of intelligent vision. Here, we propose a gate-tunable photodiode based on two-dimensional ambipolar WSe 2 with an asymmetric gate electrode, achieving high photovoltaic responsivity. By adjusting the gate voltage and keeping bias voltage zero, we can dynamically realize reconfigurable n − –p and n − –n homojunction states, as well as gate-tunable photovoltaic response characteristics that range from positive to negative. The maximum photovoltaic responsivity of the electrically tunable WSe 2 homojunction is approximately 0.4 A/W, which is significantly larger than the previously reported value ∼0.1 A/W in homojunction devices. In addition, the responsivity can be further enhanced to approximately 1.0 A/W when the n − –p photodiode operates in reverse bias mode, enabling high-sensitivity detection of targets. Our work paves the way for developing gate-tunable photodiodes with high photovoltaic responsivity and advancing high-performance intelligent vision technology.