Negative Differential Resistance Transistor with Organic p-n Heterojunction

Negative differential resistance (NDR) has large potential for versatile device applications, including high-frequency oscillators, memories, fast switches, and multilevel logic circuits. NDRs are observed at heteromaterial interfaces in resonant tunneling diodes or Esaki diodes consisting of compound semiconductors or two-dimensional (2D) atomic thin films. However, these devices suffer from poor peak-to-valley ratios (PVR) at room temperature; a cryogenic temperature is needed to improve the PVR. These negative factors are obstacles to practical applications. Here, a new NDR transistor is proposed, in which a p-n heterojunction of organic semiconductors plays a key role. Well-balanced carrier transport is manipulated at the organic p-n junction to realize outstanding NDR. Experimental and simulation analyses reveal that the observed NDR can be explained by analogy with the shoot-through current mechanism in complementary metal-oxide- semiconductor (CMOS) devices. As a result, the NDR transistor shows large PVRs of up to about 10⁴ even at room temperature.