Negative Differential Resistance in a Gated SnS ₂ /Ge Heterojunction Tunnel Diode with a High Peak-to-Valley Current Ratio of 4.7

2D/3D heterojunction tunnel transistors are promising for low-power logic applications owing to their steep subthreshold swing. Moreover, a broken-gap heterojunction is essential to enhance the current in a tunnel device. However, there is rare experimental work of 2D/3D broken-gap heterojunctions with clear negative differential resistance (NDR) and gate-tunable tunneling characteristics. In this work, we demonstrate a top-gated SnS2/p+–Ge heterojunction tunnel diode with a broken-gap alignment, exhibiting unambiguous negative differential resistance and an exceptionally high peak-to-valley ratio (PVCR) of approximately 4.7, the highest reported among all 2D/3D heterojunction tunnel diodes. Our results clearly demonstrate gate tunability of band-to-band tunneling in a SnS2/p+–Ge heterojunction diode for advanced electronic applications.