Negative Differential Resistance Transistor with Organic p‐n Heterojunction

Abstract

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.

Negative Transconductance Heterojunction Organic Transistors and their Application to Full‐Swing Ternary Circuits

“…In the conventional H‐TR, the I D value at −30 V < V G < −50 V did not exceed the I D value at V G = −15 V (i.e., half of V D = −30 V), even though the applied | V G | value was higher because PTCDI‐C13 was completely depleted at a more negative voltage bias of V G due to the high energy barrier ( Φ B ≈ 0.9 eV) as shown in Figure S2a in the Supporting Information. As a result, the conventional H‐TR had a low I ON / I OFF ratio (≈10 3 ), which confirmed the trend indicated by the results obtained for other H‐TRs in previous studies …”

“…Recently, heterojunction transistors (H-TRs) based on various semiconductor materials have been studied for MVL implementation utilizing their negative differential resistance or transconductance characteristics. The materials for H-TRs include transition metal dichalcogenides (TMDs), [4][5][6][7][8][9][10][11][12][13] organic semiconductors, [14][15][16] graphene, [17] and hybrid material combinations, including carbon nanotube (CNT)-molybdenum disulfide (MoS 2 ), [18] organic-MoS 2 , [19,20] and indium gallium zinc oxide (IGZO)-CNT. [21] www.advmat.de www.advancedsciencenews.com swing has still not been achieved in any previously reported H-TR-based ternary inverters (Tables S1 and S2, Supporting Information).…”

“…As a result, the conventional H-TR had a low I ON /I OFF ratio (≈10 3 ), which confirmed the trend indicated by the results obtained for other H-TRs in previous studies. [7,[14][15][16]18,28] In contrast, the proposed H-TR exhibited a high p-type I ON (≈1.4 µA) at V G = −50 V (Figure 1i) due to the DNTT layer, which makes contact with both the source and drain electrodes. NTC characteristics were still observed in the proposed H-TR in the middle range of V G (−35 V < V G < −29 V) ( Figure 1j).…”

“…Recently, heterojunction transistors (H‐TRs) based on various semiconductor materials have been studied for MVL implementation utilizing their negative differential resistance or transconductance characteristics. The materials for H‐TRs include transition metal dichalcogenides (TMDs), organic semiconductors, graphene, and hybrid material combinations, including carbon nanotube (CNT)‐molybdenum disulfide (MoS 2 ), organic‐MoS 2 , and indium gallium zinc oxide (IGZO)‐CNT …”

Fundamentals of Organic Anti‐Ambipolar Ternary Inverters

“…In 2018, we reported for the first time the organic “ternary” inverters based on a p ‐ n lateral heterostructure and its gate‐controlled anti‐ambipolarity 18–21. While this novel concept projected a substantial promise for fully organic flexible MVL circuits,22 still little is known about its basic operation modes and ultimate performances associated with the fundamental device physics.…”