Electrical and reliability characteristics of polycrystalline silicon thin-film transistors with high-κ Eu2O3 gate dielectrics

Abstract

In this study, we developed a high-performance low-temperature polycrystalline silicon thin-film transistor (LTPS-TFT) incorporating an ultra thin Eu 2 O 3 gate dielectric. High-j Eu 2 O 3 LTPS-TFT annealed at 500 C exhibits a low threshold voltage of 0.16 V, a high effective carrier mobility of 44 cm 2 /V-s, a small subthreshold swing of 142 mV/decade, and a high I on /I off current ratio of 1.34 Â 10 7. These significant improvements are attributed to the high gate-capacitance density due to the adequate quality of Eu 2 O 3 gate dielectric with small interfacial layer of effective oxide thickness of 2.5 nm. Furthermore, the degradation mechanism of positive bias temperature instability was studied for a high-k Eu 2 O 3 LTPS-TFT device. V

Asymmetric Driving Current Modification of CMOS LTPS-TFTs With ${\rm HfO}_{2}$ Gate Dielectric

“…The structure is the same as [13]. The threshold voltage V TH is defined as the gate voltage at which the drain current reaches 10 nA × W/L and | V D | = 0.1 V. The electron and hole μ FE are extracted from the maximum transconductance (G m ) and gate capacitance density of each device [11]- [13]. Over ten devices of each process condition are measured to confirm the results.…”

Threshold Voltage Reduction and Mobility Improvement of LTPS-TFTs With NH₃ Plasma Treatment

“…A 60-nm HfO 2 was deposited by physical vapor deposition system at room temperature. For control device (without NH 3 plasma treatment) and the PIL removal device, a native growth interfacial layer (NIL) between HfO 2 and poly-Si channel can be found (not shown) because the oxygen atoms of high-κ dielectric can react with Si to form an SiO x layer [18]- [21]. For the NH 3 plasma treated device, the PIL SiN x would be oxidized by HfO 2 and converted to SiO x N y .…”

Solution-Processed Rare-Earth Oxide Thin Films for Alternative Gate Dielectric Application

“…Among diverse RE materials, the most stable compounds are RE oxides (REOs), in which most of the RE elements hold typically a trivalent state with the general formula of sesquioxide, Ln 2 O 3 (e.g., Sc 2 O 3 , Y 2 O 3 , La 2 O 3 , Sm 2 O 3 , and Er 2 O 3 ), while for Ce, Pr, and Tb, more stable oxides exist as CeO 2 , Pr 6 O 11 , and Tb 4 O 7 , respectively . The applications of REOs have now been broadened to luminescent, optical, and dielectric materials. − Previous studies on REOs revealed that they possess remarkable electrical properties, such as high relative dielectric constant, large areal capacitance, superior electrical breakdown strength, high transparency, and superior thermal stability which fulfill the requirements of dielectrics in electronics, especially thin-film transistors (TFTs). ,− Except for Pm 2 O 3 due to its radioactive property, all the other 16 REOs films have been studied and employed as gate dielectrics in recent years, and the results revealed that the REOs are promising candidates as alternative gate dielectrics to traditional SiO 2 . − Therefore, REOs, together with other potential oxides (e.g., Al 2 O 3 , ZrO 2 , and HfO 2 ), have also been considered as solutions to the problems of large leakage current, high standby power consumption, and inferior gate dielectric reliability for continued downscaling of electronics. − Usually, these oxides were prepared by some traditional costly vacuum-based techniques, such as physical vapor deposition (PVD), chemical vapor deposition (CVD), and atomic layer deposition (ALD), which are expensive and time-consuming. ,,− In this regard, solution-processable dielectrics are more favorable in electronics as they are cost-effective and can be manufactured in large amounts. − Sol–gel method is a well-known and popular technique as it offers the possibility of tuning properties of resulting products by adjusting the precursor solutions easily. It has been empolyed in numerous fields including the preparation of high performance dielectrics.…”