Low-power-consumption CMOS inverter array based on CVD-grown p-MoTe2 and n-MoS2

High-Performance CMOS Inverter Array with Monolithic 3D Architecture Based on CVD-Grown n-MoS2 and p-MoTe2

In this work, monolithic three-dimensional complementary metal oxide semiconductor (CMOS) inverter array has been fabricated, based on large-scale n-MoS₂ and p-MoTe₂ grown by the chemical vapor deposition method. In the CMOS device, the n- and p-channel field-effect transistors (FETs) stack vertically and share the same gate electrode. High k HfO₂ is used as the gate dielectric. An Al₂ O₃ seed layer is used to protect the MoS₂ from heavily n-doping in the later-on atomic layer deposition process. P-MoTe₂ FET is intentionally designed as the upper layer. Because p-doping of MoTe₂ results from oxygen and water in the air, this design can guarantee a higher hole density of MoTe₂ . An HfO₂ capping layer is employed to further balance the transfer curves of n- and p-channel FETs and improve the performance of the inverter. The typical gain and power consumption of the CMOS devices are about 4.2 and 0.11 nW, respectively, at V_DD of 1 V. The statistical results show that the CMOS array is with high device yield (60%) and an average voltage gain value of about 3.6 at V_DD of 1 V. This work demonstrates the advantage of two-dimensional semi-conductive transition metal dichalcogenides in fabricating high-density integrated circuits.

Low-Power Complementary Inverter Based on Graphene/Carbon-Nanotube and Graphene/MoS2 Barristors

The recent report of a p-type graphene(Gr)/carbon-nanotube(CNT) barristor facilitates the application of graphene barristors in the fabrication of complementary logic devices. Here, a complementary inverter is presented that combines a p-type Gr/CNT barristor with a n-type Gr/MoS2 barristor, and its characteristics are reported. A sub-nW (~0.2 nW) low-power inverter is demonstrated with a moderate gain of 2.5 at an equivalent oxide thickness (EOT) of ~15 nm. Compared to inverters based on field-effect transistors, the sub-nW power consumption was achieved at a much larger EOT, which was attributed to the excellent switching characteristics of Gr barristors.

Overall High-Performance Near-Infrared Photodetector Based on CVD-Grown MoTe2 and Graphene Vertical vdWs Heterostructure

Two-dimensional (2D) materials, such as graphene and transition metal dichalcogenides (TMDCs), are highly appealing in the fields of electronics, optoelectronics, energy, etc. Graphene, with high conductivity and high carrier mobility, is an excellent candidate for transparent electrodes. TMDCs have remarkably strong light absorption in the range of visible to infrared wavelength. High-performance photodetectors are expected to achieve through the combination of graphene and TMDCs. Nowadays, near-infrared (NIR) photodetectors play significant roles in many areas. MoTe2 with bandgap energy of about 1.0 eV in its bulk form is a promising material for cost-saving NIR photodetectors. Thus far, only a few of the reported studies on NIR photodetectors built on MoTe2/graphene heterostructures have achieved high responsivity and short response time simultaneously in one device. In this study, we fabricate graphene–MoTe2–graphene vertical van der Waals heterostructure devices through chemical vapor deposition (CVD) growth, wet transfer method, and dry etching technique. Under 1064 nm laser illumination, we acquire responsivity of as high as 635 A/W and a response time of as short as 19 μs from the as-fabricated device. Moreover, we acquire higher responsivity of 1752 A/W and a shorter response time of 16 μs from the Al2O3-encapsulated device. Our research drives the application of 2D materials in the NIR wavelength range.