Trap density probing on top-gate MoS₂nanosheet field-effect transistors by photo-excited charge collection spectroscopy

Abstract

Two-dimensional (2D) molybdenum disulfide (MoS₂) field-effect transistors (FETs) have been extensively studied, but most of the FETs with gate insulators have displayed negative threshold voltage values, which indicates the presence of interfacial traps both shallow and deep in energy level. Despite such interface trap issues, reports on trap densities in MoS₂ are quite limited. Here, we probed top-gate MoS₂ FETs with two- (2L), three- (3L), and four-layer (4L) MoS₂/dielectric interfaces to quantify deep-level interface trap densities by photo-excited charge collection spectroscopy (PECCS), and reported the result that deep-level trap densities over 10(12) cm(-2) may exist in the interface and bulk MoS₂ near the interface. Transfer curve hysteresis and PECCS measurements show that shallow traps and deep traps are not that different in density order from each other. We conclude that our PECCS analysis distinguishably provides valuable information on deep level interface/bulk trap densities in 2D-based FETs.

HfSe 2 and ZrSe 2 : Two-dimensional semiconductors with native high-κ oxides

“…Here, C is the net capacitance per area, calculated from the series combination of C ox and a finite semiconductor depth ( C s with κ HfSe2 = 8.05) ( 47 ), assuming a 2DEG peaked at the center of flake thickness ( 48 ). Despite a lower gate capacitance than that of conventional HFETs, dominated by the single back gate across all sample thicknesses, a range of N IT = 3 × 10 12 to 8 × 10 12 cm −2 for the HfSe 2 /HfO x /AlO x stack mirrors the 2.5 × 10 12 to 7.5 × 10 12 cm −2 estimated for MoS 2 /AlO x top-gate interfaces via hysteresis, SS, and charge collection spectroscopy ( 49 , 50 ). Figure 5C shows an Arrhenius analysis of the trap thermal response, fitting an exponential evolution of density N IT with temperature by an activation energy E A ≈ 26 to 32 meV comparable to the Boltzmann energy at room temperature.…”

CdS/MoS 2 heterojunction-based photoelectrochemical DNA biosensor via enhanced chemiluminescence excitation

“…Considering the broad application of MoS 2 nanomaterial in field effect transistor (Choi et al, 2015;Singh et al, 2014), photocatalysis (Kang et al, 2015) and bioanalysis , here, a highly dispersed suspension of MoS 2 QDs was prepared by liquid exfoliation method. Compared to bulk MoS 2 (Fig.…”

Full Energy Spectra of Interface State Densities for n‐ and p‐type MoS2 Field‐Effect Transistors

“…Here, the recent demonstration of a natural thin‐body MoS 2 FET with an effective channel length of ≈ 3.9 nm has facilitated research on 2D layered channels due to overcoming the scaling limit of ≈ 5 nm for Si gate length . Although the dangling‐bond‐free surface of the layered channel is expected to ideally provide an electrically inert interface, there are many reports on the wide range of interface state densities ( D it ) from 10 11 to 10 13 eV −1 cm −2 for high‐ k top‐gate n ‐MoS 2 FET in reality, which must be reduced to improve the device performance. To date, several physical origins for D it have been proposed, which are summarized in Figure a.…”