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This paper investigates the low-frequency noise properties of multilayer WSe2 field effect transistors (FETs) in subthreshold, linear, and saturation regime. The measured noise power spectral density of drain current (SID) shows that the low-frequency noise in multilayer WSe2 FET fits well to a 1/fγ power law with γ ~ 1 in the frequency range of 10Hz-200Hz. From the dependence of SID on the drain current, carrier mobility fluctuation is considered as a dominant low frequency noise mechanism from all operation regimes in multilayer WSe2 FET. Extracted Hooge's parameter in this study is within the value of 0.12, comparable to those of the transition metal dichalcogenide FETs in recent reports. [ABSTRACT FROM AUTHOR]

This study examined the relationship between the mobility and bias stability of pentacene-based organic field-effect transistors (OFETs) regarding a self-assembled monolayer (SAM) treatment. For this systematic study, four types of silazane-based SAMs with different alkyl chain lengths in the range of 1-8 were used. Silazane-based SAMs have an advantage of processability due to the mild reaction conditions. The mobility was increased from 0.29 without SAM to 0.46, 0.61, 0.65, and 0.84 cm²/V s after the SAM-treatment with an alkyl chain length of 1, 3, 4, and 8, respectively. On the other hand, inverse proportional relationship was observed between the bias stability and SAM alkyl chain length. Under high gate bias stress (equivalent to electric field of 3 MV/cm) for 2 h, the threshold voltage shift of the OFET was decreased from 12.19V without SAM to 5.69V with a short SAM-treatment (alkyl chain length of 1) and 7.14V with a long SAM-treatment (alkyl chain length of 8). This is the significant finding that there was a tradeoff relationship between the mobility and bias stability of OFETs concerning the SAM alkyl chain length. To overcome this tradeoff, a method for surface engineering using two-step SAM-treatment was introduced. By treating long SAM and short SAM in sequence, both the high mobility and good bias stability were achieved. With two-step SAM-treatment, the OFET showed high mobility as a long SAM-treated OFET and good bias stability as a short SAM-treated OFET. [ABSTRACT FROM AUTHOR]

A high-gain complementary metal-oxide-semiconductor (CMOS) logic inverter was implemented by fabricating p- and n-type field effect transistors (FETs) based on multi-layer WSe2 on the same wafer. Au as a high work-function metal is contacted to WSe2 for the source/drain of the p-type FET. The n-type FET has an Al electrode contacted to WSe2 for the source/drain. Both FETs were designed to have similar on-current densities (>10−7 A μm−1) and high on/off current ratios (>106). The inverter shows excellent switching characteristics including relatively high voltage gains (>25) and high noise margins (>0.9) in the range of supply voltage from 2 V to 8 V. This work has a great significance in the realization of a CMOS logic gate based on WSe2 without an additional doping scheme. [ABSTRACT FROM AUTHOR]

We demonstrated highly stable multilayer molybdenum disulfide (MoS2) field-effect transistors (FETs) with negligible hysteresis gap (ΔVHYS ∼ 0.15 V) via a multiple annealing scheme, followed by systematic investigation for long-term air stability with time (∼50 days) of MoS2 FETs with (or without) CYTOP encapsulation. The extracted lifetime of the device with CYTOP passivation in air was dramatically improved from 7 to 377 days, and even for the short-term bias stability, the experimental threshold voltage shift, outstandingly well-matched with the stretched exponential function, indicates that the device without passivation has approximately 25% larger the barrier distribution (ΔEB = kBTo) than that of a device with passivation. This work suggests that CYTOP encapsulation can be an efficient method to isolate external gas (O2 and H2O) effects on the electrical performance of FETs, especially with low-dimensional active materials like MoS2. [ABSTRACT FROM AUTHOR]