Channel length dependence of field-effect mobility ofc-axis-aligned crystalline In–Ga–Zn–O field-effect transistors

Abstract

Field-effect transistors (FETs) with c-axis-aligned crystalline In-Ga-Zn-O (CAAC-IGZO) active layers have extremely low off-state leakage current. Exploiting this feature, we investigated the application of CAAC-IGZO FETs to LSI memories. A high on-state current is required for the high-speed operation of these LSI memories. The field-effect mobility μ FE of a CAAC-IGZO FET is relatively low compared with the electron mobility of singlecrystal Si (sc-Si). In this study, we measured and calculated the channel length L dependence of μ FE for CAAC-IGZO and sc-Si FETs. For CAAC-IGZO FETs, μ FE remains almost constant, particularly when L is longer than 0.3 µm, whereas that of sc-Si FETs decreases markedly as L shortens. Thus, the μ FE difference between both FET types is reduced by miniaturization. This difference in μ FE behavior is attributed to the different susceptibilities of electrons to phonon scattering. On the basis of this result and the extremely low off-state leakage current of CAAC-IGZO FETs, we expect high-speed LSI memories with low power consumption.

High-Field Transport and Velocity Saturation in Synthetic Monolayer MoS2

“…Although v sat values reported for these materials are somewhat higher than our results for 1L MoS 2 , graphene and thick BP have very small band gaps (0 and <0.3 eV, respectively) and are therefore not well-suited for logic applications. By contrast, the other materials ,− shown in Figure have only been measured in regimes where they maintain their bulk properties (i.e., thicknesses ≫ 1 nm) and so can only be indirectly compared to 1L MoS 2 . Thus, our measurements of v sat in monolayer MoS 2 provide promising results for logic transistor applications of atomically thin 2D materials.…”

“…Summary of saturation velocity versus band gap for various bulk and a few layered materials at room temperature. ,− With the exception of graphene, which lacks a band gap, 1L MoS 2 is the only atomically thin (sub-1 nm) material shown, yet retains appreciable v sat . (Note the electronic band gap of 1L MoS 2 is greater than the optical gap typically obtained from photoluminescence experiments …”

Crystalline IGZO ceramics (crystalline oxide semiconductor)–based devices for artificial intelligence

“…Figure A shows L dependence of drift mobility of Si FET and OSFET with the same drain voltage. The drift mobility of OSFET was obtained in reference to theoretical studies . Figure A also shows measurement results of field‐effect mobility of the OSFET.…”

“…The drift mobility of OSFET was obtained in reference to theoretical studies. 30 Figure 12A also shows measurement results of field-effect mobility of the OSFET. The measurement results meet the theoretical studies.…”

P-4: Electrical Characteristics of Dual-Gate CAAC-IGZO FET with Self-Aligned Top Gate

“…Actually, high-definition displays and flexible displays using IGZO FETs have been provided [1,2]. In recent years, crystalline IGZO, especially c-axis aligned crystalline IGZO (CAAC-IGZO), have been studied actively [3][4][5][6][7][8][9][10].…”