S. Y. Yang

Bio: S. Y. Yang is an academic researcher from Chinese Academy of Sciences. The author has contributed to research in topics: Polyimide & Thermal decomposition. The author has an hindex of 11, co-authored 14 publications receiving 512 citations.

Synthesis and characterization of soluble fluorine‐containing polyimides based on 1,4‐bis(4‐amino‐2‐trifluoromethylphenoxy)benzene

Abstract: The synthesis and properties of a class of soluble fluorine-containing aromatic polyimides are described. Substituents of trifluoromethyl groups on the aromatic rings of paralinked aromatic ether diamine conferred the polymer prepared thereof with enhanced solubility, low-moisture absorption, and low dielectric constants. The polyimides also exhibited exceptional thermal stability, good mechanical properties, and excellent hygrothermal resistance. These outstanding combined features ensure the polymers are desirable candidate materials for advanced microelectronics applications. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2581–2590, 2001

Organosoluble and transparent polyimides derived from alicyclic dianhydride and aromatic diamines

Abstract: Organosoluble polyimides were synthesized with the alicyclic dianhydride 1,8-dimethylbicyclo[2,2,2]oct-7-ene-2,3,5,6-tetracarboxylic dianhydride and aromatic diamines. The polyimides possessed good solubility both in strong dipolar solvents and in common solvents; the thermal decomposition temperature of the polyimides exceeded 420 °C. Strong and flexible films of the polyimides, with the cutoff of ultraviolet–visible absorption lower than 310–320 nm, exhibited good features as the alignment layers for nematic liquid crystals with pretilt angles of 1.5–2.9°. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 110–119, 2002

Synthesis and characterization of organosoluble polyimides with trifluoromethyl‐substituted benzene in the side chain

Abstract: New aromatic diamines substituted with a trifluoromethyl group in the side chain, 2,4-diamino-3′-trifluoromethylazobenzene, 2,4-diamino-1-[(4′-trifluoromethylphenoxy) phenyl] aniline, and 3,5-diamino-1-[(4′-trifluoromethyl phenoxy) phenyl] benzamide were synthesized and characterized and used to prepare polyimides by a one-step high-temperature polycondensation method. Experimental results indicated that the prepared polyimides possess good solubility in strong organic solvents such as N-methyl-2-pyrrolidinone, N,N′-dimethylformamide, and N,N′-dimethylacetamide. Homogeneous solutions with solid contents as high as 15–20% can be prepared, which are stable for storing longer than 2 weeks at room temperature. The polyimides exhibited glass-transition temperatures of 249–292 °C and good thermal stability. The PI-Ic and PI-IIIc films prepared by casting the fully imidized polymer solutions showed good transparency with cutoff wavelengths at 320–330 nm. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1572–1582, 2002

Synthesis and characterization of novel fluorinated polyimides derived from 4,4′‐[2,2,2‐trifluoro‐1‐(3‐trifluoromethylphenyl)ethylidene]diphthalic anhydride and aromatic diamines

Abstract: A novel fluorinated aromatic dianhydride, 4,4′-[2,2,2-trifluoro-1-(3-trifluoromethyl-phenyl)ethylidene]diphthalic anhydride (TFDA) was synthesized by coupling of 3′-trifluoromethyl-2,2,2-trifluoroacetophenone with o-xylene under the catalysis of trifluoromethanesulfonic acid, followed by oxidation of KMnO4 and dehydration. A series of fluorinated aromatic polyimides derived from the novel fluorinated aromatic dianhydride TFDA with various aromatic diamines, such as p-phenylenediamine (p-PDA), 4,4′-oxydianiline (ODA), 1,4-bis(4-aminophenoxy)benzene (p-APB), 1,3-bis(4-amino-phenoxy)benzene (m-APB), 4-(4-aminophenoxy)-3-trifluoromethylphenylamine (3FODA) and 1,4-bis(4-amino-2-trifluoromethylphenoxy)benzene (6FAPB), were prepared by polycondensation procedure. All the fluorinated polyimides were soluble in many polar organic solvents such as NMP, DMAc, DMF, and m-cresol, as well as some of low boiling point organic solvents such as CHCl3, THF, and acetone. Homogeneous and stable polyimide solutions with solid content as high as 35–40 wt % could be achieved, which were prepared by strong and flexible polyimide films or coatings. The polymer films have good thermal stability with the glass transition temperature of 232–322 °C, the temperature at 5% weight loss of 500–530 °C in nitrogen, and have outstanding mechanical properties with the tensile strengths of 80.5–133.2 MPa as well as elongations at breakage of 7.1–12.6%. It was also found that the polyimide films derived from TFDA and fluorinated aromatic diamines possess low dielectric constants of 2.75–3.02, a low dissipation factor in the range of 1.27–4.50 × 10−3, and low moisture absorptions <1.3%. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4143–4152, 2004

$\hbox{ZrO}_{2}$ -Based Memory Cell With a Self-Rectifying Effect for Crossbar WORM Memory Application

Abstract: A memory cell based on n+-Si/ZrO2/Pt structure with self-rectifying properties is demonstrated for write-once-read-many-times (WORM) memory application. The fresh devices can be set to a low resistance state (LRS) as an antifuse and keep in LRS permanently with a rectification ratio exceeding 104. The memory devices show a large on/off ratio of about 106 and narrow resistance distributions before and after programming. The different transport mechanisms of forward and reverse currents are studied, which are responsible for this reliable self-rectifying characteristic. The demonstrated memory cell with self-rectifying properties has potential application in high-density passive crossbar WORM memory.

A Functional Hybrid Memristor Crossbar-Array/CMOS System for Data Storage and Neuromorphic Applications

Abstract: Crossbar arrays based on two-terminal resistive switches have been proposed as a leading candidate for future memory and logic applications. Here we demonstrate a high-density, fully operational hybrid crossbar/CMOS system composed of a transistor- and diode-less memristor crossbar array vertically integrated on top of a CMOS chip by taking advantage of the intrinsic nonlinear characteristics of the memristor element. The hybrid crossbar/CMOS system can reliably store complex binary and multilevel 1600 pixel bitmap images using a new programming scheme.

Access devices for 3D crosspoint memorya)

Abstract: The emergence of new nonvolatile memory (NVM) technologies—such as phase change memory, resistive, and spin-torque-transfer magnetic RAM—has been motivated by exciting applications such as storage class memory, embedded nonvolatile memory, enhanced solid-state disks, and neuromorphic computing. Many of these applications call for such NVM devices to be packed densely in vast “crosspoint” arrays offering many gigabytes if not terabytes of solid-state storage. In such arrays, access to any small subset of the array for accurate reading or low-power writing requires a strong nonlinearity in the IV characteristics, so that the currents passing through the selecteddevices greatly exceed the residual leakage through the nonselecteddevices. This nonlinearity can either be included explicitly, by adding a discrete access device at each crosspoint, or implicitly with an NVM device which also exhibits a highly nonlinear IV characteristic. This article reviews progress made toward implementing such access device functionality, focusing on the need to stack such crosspoint arrays vertically above the surface of a silicon wafer for increased effective areal density. The authors start with a brief overview of circuit-level considerations for crosspoint memory arrays, and discuss the role of the access device in minimizing leakage through the many nonselected cells, while delivering the right voltages and currents to the selected cell. The authors then summarize the criteria that an access device must fulfill in order to enable crosspoint memory. The authors review current research on various discrete access device options, ranging from conventional silicon-based semiconductor devices, to oxide semiconductors, threshold switch devices, oxide tunnel barriers, and devices based on mixed-ionic-electronic-conduction. Finally, the authors discuss various approaches for self-selected nonvolatile memories based on Resistive RAM.

Thermally Reversible Cross‐Linked Polyamides with High Toughness and Self‐Repairing Ability from Maleimide‐ and Furan‐Functionalized Aromatic Polyamides

Abstract: Polyamides having various amounts of maleimide (PA-MI) and furan (PA-F) pendent groups, respectively, as well as their cross-linked polymers (PA-MI/PA-F) were prepared. PA-MI/PA-F cross-linked polymers showed thermally reversible cross-linking behavior via Diels-Alder (DA) and retro-DA reactions. Cross-linked PA-MI/PA-F films exhibited enhanced toughness and mechanical properties compared to PA-MI and PA-F precursors. Moreover, PA-MI/PA-F films also showed thermal self-repairing behavior, which was observed in the micrographs and instron tests.