We present a tunneling
field-effect transistor based on a vertical heterostructure of highly
p-doped silicon and n-type MoS2. The resulting p–n
heterojunction shows a staggered band alignment in which the quantum
mechanical band-to-band tunneling probability is enhanced. The device
functions in both tunneling transistor and conventional transistor
modes, depending on whether the p–n junction is forward or
reverse biased, and exhibits a minimum subthreshold swing of 15 mV/dec,
an average of 77 mV/dec for four decades of the drain current, a high
on/off current ratio of approximately 107 at a drain voltage
of 1 V, and fully suppressed ambipolar behavior. Furthermore, low-temperature
electrical measurements demonstrated that both trap-assisted and band-to-band
tunneling contribute to the drain current. The presence of traps was
attributed to defects within the interfacial oxide between silicon
and MoS2.
2D‐layered transition metal dichalcogenides (TMDCs) such as molybdenum disulfide (MoS2) are promising materials for next‐generation active matrix organic light‐emitting diode (AMOLED) display technology owing to their high mobility and large bandgap size. However, practical applications of TMDCs in driving circuits for flexible displays remain challenging because of the lack of high‐quality large‐area thin films and suitable fabrication processes. Here, millimeter‐scale large‐area bilayer or trilayer MoS2 thin films are synthesized through chemical vapor deposition (CVD) and an AMOLED driver circuit array consisting of bottom‐gate staggered CVD‐grown MoS2 thin‐film transistors is fabricated on a flexible polyimide substrate. The flexible driver circuit exhibits a stable switching and driving operation under tensile strain induced by a bending radius of 3.5 mm, showing field‐effect mobilities of up to ≈9 cm2 V−1 s−1, large ON‐state current density (up to ≈5 µA µm−1), and high ON/OFF‐state drain current ratio (maximum value of over 108) with an operating gate voltage below 10 V. The results demonstrate that MoS2 backplanes are among the promising candidates for next‐generation deformable and transparent AMOLED displays.
Two-dimensional (2D) materials including graphene and transition metal dichalcogenides (TMDCs) have attracted great interest as new electronic materials, given their superior properties such as optical transparency, mechanical flexibility, and stretchability, especially for application in next-generation displays. In particular, the integration of graphene and TMDCs enables the implementation of 2D materials-based thin-film transistors (TFTs) in stretchable displays, given that TFTs are the fundamental element of various modern devices. In the present study, we demonstrate chemical-vapor-deposited molybdenum disulfide and graphene-based TFTs on a polymer substrate and investigate the electrical characteristics of TFTs under mechanical deformation to determine the stretchability of our devices. Furthermore, the mechanisms leading to TFT performance degradation are investigated, as they relate to the change in the contact resistance that is closely associated with the relative deformation of 2D materials under mechanical stress. Therefore, the synergetic integration of 2D materials with versatile electrical properties provides an important strategy for creating 2D materials-based stretchable TFTs, thus extending the excellent potential of 2D materials as innovative materials for stretchable active-matrix displays.
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