The enhanced characteristics of bipolar phototransistor with huge amplification

Heterojunction devices based on low-dimensional materials have the potential for convenient and efficient photodetection applications. In this study, we demonstrate a van der Waals (vdW) heterojunction device constructed by p-ZrGeTe₄ and n-MoS₂. Forming a p-n junction, the response speed of the device increased by 6 orders of magnitude compared to devices with individual MoS₂. To further improve the responsivity of the device, a bipolar phototransistor (PTD) was prepared based on the p-n junction. The PTD achieves the photocurrent gain of almost 40. This PTD achieves high responsivity of 1.48 A W⁻¹, and the corresponding specific detectivity can reach 3 × 10¹⁴ Jones in low frequencies. Under low frequencies, the noise of the device is dominated by generation–recombination noise; and as the frequency increases, it gradually becomes dominated by 1/f noise. The PTD is competitive in optoelectronics and promising in high-performance integrated devices.