Polarization-induced photocurrent switching effect in heterojunction photodiodes

The unipolar photocurrent in conventional photodiodes (PDs) based on photovoltaic effect limits the output modes and potential versatility of these devices in photodetection. Bipolar photodiodes with photocurrent switching are emerging as a promising solution for obtaining photoelectric devices with unique and attractive functions, such as optical logic operation. Here, we design an all-solid-state chip-scale ultraviolet (UV) PD based on a hybrid GaN heterojunction with engineered bipolar polarized electric field. By introducing the polarization-induced photocurrent switching effect, the photocurrent direction can be switched in response to the wavelength of incident light at 0 V bias. In particular, the photocurrent direction exhibits negative when the irradiation wavelength is less than 315 nm, but positive when the wavelength is longer than 315 nm. The device shows a responsivity of up to −6.7 mA/W at 300 nm and 5.3 mA/W at 340 nm, respectively. In particular, three special logic gates in response to different dual UV light inputs are demonstrated via a single bipolar PD, which may be beneficial for future multifunctional UV photonic integrated devices and systems.