Thickness‐Dependent, Gate‐Tunable Rectification and Highly Sensitive Photovoltaic Behavior of Heterostructured GeSe/WS2 p–n Diode

Abstract The p–n heterojunction fabricated by the vertical stacking of 2D materials is highly relevant to modern electronics and optoelectronic devices. This research reports a novel p‐GeSe/n‐WS 2 heterostructured diode exhibiting prominent thickness‐dependent and gate‐tunable rectification behavior. The rectification ratio increases as the thickness of WS 2 is increased. A rectification ratio of 10 4 is achieved by successfully sweeping the back‐gate voltage. The modulation in the rectification behavior is ascribed to the interlayer electron‐hole recombination. Density functional theory (DFT) calculations further support the thickness‐dependent, gate‐modulated experimental results. The diode exhibits efficient photodetection with promising figures of merit. The photoresponse is investigated under the illuminations of λ equal to 365, 530, and 850 nm. The diode displays a high responsivity of 845 mA W −1 at 850 nm. In addition, the diode exhibits a detectivity of 3.28 × 10 8 Jones, normalized photocurrent to dark current ratio (NPDR) of 1 × 10 8 W −1 , noise equivalent power (NEP) of 1.9 × 10 −12 WHz −1/2 , and a rise time of 10 ms. The p‐GeSe/n‐WS 2 diode demonstrates excellent rectification and optoelectronic characteristics.