研究領域:
研究領域:
(A) Nanoelectronics group
Spintronics
SL-MTJ
(superlattice based MTJ) and MTJ (magnetic tunnel junctions)
SS-MRAM
(superlattice-based STT-MRAM or SL-STT-MRAM), STT- MRAM (spin-transfer torque
MRAM), and MRAM (magnetoresistive random access memory)
詳細介紹
Graphene
and topological insulator, and spin-valve
(B) Photonics group
Photonic
crystals, topological photonics, and quasicrystals
Waveguides,
integrated optics, and multilayers
Microring
resonators
Graphene
具有超晶格的STT-MARM(SS-MARM或SL-STT-MARM)之介紹
磁性隨機存取記憶體(non-volatile magnetic random access memory, MRAM)為非揮發性記憶體(non-volatile memory)，其讀寫是以自旋電子(spintronics)進行操作，具有較少的能量消耗、零待機耗能、非揮發、高耐用性和高密度等優勢。磁性穿遂接面(magnetic tunnel junctions, MTJ)為 MRAM中的單位記憶元，更是整個元件最核心的部分。
國立臺灣大學電子與光子學實驗室研究團隊，開發了一種具有超晶格勢壘 (superlattice barrier)的自旋轉移力矩式磁性隨機存取記憶體(STT-MRAM)，稱為SS-MARM或SL-STT-MARM。SS-MARM同時實現了超低功耗、超高磁阻比值(magnetoresistance ratio, MR ratio)、高速切換和低電阻面積乘積(resistance-area product, RA)。SS-MRAM使用一種人造材料(稱為超晶格)來替代傳統STT-MRAM中的單晶 (001) MgO。超晶格由交替的金屬和絕緣組成，其中在絕緣材料中能夠使用非晶(amorphous) 材料，而不是單晶材料(single crystalline) 。因此，與傳統的STT-MRAM相比，SS-MRAM性能大幅提升，且具有更高的可靠性，製造也更為容易。SS-MRAM可將傳統STT-MRAM的寫入功率和RA值降低90％以上，此外， SS-MRAM的MR ratio和切換速度可以提高10倍以上，這些結果已在一些國際期刊和會議上發表。
特別值得注意的是，SS-MRAM中的絕緣層可以由任意的非晶材料製成，而不是使用製程要求極高的單晶材料。與傳統的STT-MRAM相比，SS-MRAM的製造變得更加容易和簡單。而且，由於SS-MRAM使用較為穩定的非晶材料，而不是不穩定的單晶材料。所以可以避免由於重複寫入，而引起的單晶材料劣化(degradation)，影響性能。因此，SS-MRAM的可靠性和耐用性將比傳統的STT-MRAM提高許多等級，趨近一般DRAM或SRAM。
我們現在正在開發、測試和擴展SS-MRAM的元件性能上尋求與業界合作。
相關期刊發表
A. News and Website Reports
[1] R. Mertens, 2019, “New super-lattice SL-STT-MRAM enable faster and more efficient memory architecture,” MRAM-Info, Posted: Dec 23, 2019. Read More
[2] Nanowerk News, 2020, “A superlattice based STT-MRAM with extra-high performance,” Nanowerk, Posted: Jan 17, 2020. Read More
[3] DigiTimes, 2020, “Taiwan university develops next-gen memory technology,” DigiTimes, Posted: Jun. 10, 2020. Read More
[4] 台大校訊1422期:“臺大工科系薛文証教授團隊開發次世代記憶體SS-MRAM獲MRAM-Info以及Nanowerk News報導”(2020/2/5) 報導連結；
台灣大學焦點新聞:“臺大工科系薛文証教授團隊開發次世代記憶體SS-MRAM獲報導”(2020/02/10) 報導連結；
臺灣大學第174期校友電子報:“臺大工科系薛文証教授團隊開發次世代記憶體SS-MRAM獲MRAM-Info以及Nanowerk News報導”(2020/3) 報導連結
[5] 台灣大學工學院簡訊230期:“【工科海洋系薛文証教授團隊】開發次世代記憶體SS-MRAM獲MRAM-Info專業網站撰文介紹”(2020/2/15) 報導連結
[6] DigiTimes科技網: “台大團隊突破SS-MRAM關鍵技術 搶攻次世代夢幻記憶體”(2020/6/10) 報導連結
B. Scientific Journals and Conferences
[1] C. H. Chen and W. J. Hsueh*, 2014, “Enhancement of tunnel magnetoresistance in magnetic tunnel junction by a superlattice barrier,” Appl. Phys. Lett., Vol. 104, pp. 042405. Read More
[2] C. H. Chen, C. H. Chang, Y. H. Cheng, and W. J. Hsueh*, 2015, “Ultrahigh tunnel magnetoresistance using an artificial superlattice barrier with copper and aluminum oxide,” Europhys. Lett. Vol. 111, pp. 47005. Read More
[3] C. H. Chen, Y. H. Cheng, C. W. Ko, and W. J. Hsueh*, 2015, “Enhanced spin-torque in double-barrier magnetic tunnel junctions by a nonmagnetic-metal spacer,” Appl. Phys. Lett., Vol. 107, pp. 152401. Read More
[4] C. H. Chen, P. Tseng, C. W. Ko, and W. J. Hsueh*, 2017, “Huge spin transfer torque in a magnetic tunnel junction by a superlattice barrier,” Phys. Lett. A, Vol. 381, pp. 3124-3128. Read More
[5] A. Sharma, A. A. Tulapurkar, and B. Muralidharan, 2018, “Band-pass Fabry-Pèrot magnetic tunnel junctions,” Appl. Phys. Lett., Vol. 112, pp. 192404. Read More
[6] P. Tseng and W. J. Hsueh*, 2018, “Enhancement of spin-transfer torque in superlattice-barrier magnetic tunnel junctions,” Global Conference on Magnetic and Magnetism Materials (GMMM 2018), July, 23-24, Osaka, Japan. Read More
[7] P. Tseng and W. J. Hsueh*, 2019, “Ultra-giant magnetoresistance in graphene-based spin valves with gate-controlled potential barriers,” New J. Phys., Vol. 21, No. 113035. Read More
期刊發表
(2010-2018):
1. Y. C. Lin, C. H. Tsou and and W. J. Hsueh*, 2018 “Ultra-slow light in one-dimensional Cantor photonic crystals,” Opt. Lett., Vol. 43, No. 17, pp. 4120-4123. (SCI, Optics, RF: 16/95=16.8%, IF:3.866)
2. P. Tseng, C. H. Chen, S. A. Hsu, and W. J. Hsueh*, 2018, “Large negative differential resistance in graphene nanoribbon superlattices,” Phys. Lett. A, Vol. 382, pp. 1427-1431. (SCI, Physics, multidisciplinary, RF: 33/81=40.7%, IF:2.087)
3. C. H. Chen, P. Tseng, C. W. Ko, and W. J. Hsueh*, 2017, “Huge spin transfer torque in a magnetic tunnel junction by a superlattice barrier,” Phys. Lett. A, Vol. 381, pp. 3124-3128. (SCI, Physics, multidisciplinary, RF: 35/78=44.9%, IF:1.863)
4. C. H. Chen, P. Tseng, Y. Y. Yang and W. J. Hsueh*, 2017, “Enhancement of thermal spin transfer torque by double-barrier magnetic tunnel junctions with a nonmagnetic metal spacer,” J. Phys.: Condens. Matter, Vol. 29, pp. 025806. (SCI, Physics, condensed matter, RF: 27/67=40.3%, IF:2.617)
5. C. H. Chen, P. Tseng, and W. J. Hsueh*, 2016, “Quasi-Dirac points in one-dimensional graphene superlattices,” Phys. Lett. A, Vol. 380, pp. 2957-2961. (SCI, Physics, multidisciplinary, RF: 27/79=34.2%, IF:1.772)
6. C. H. Chen, Y. H. Cheng, C. W. Ko, and W. J. Hsueh*, 2015, “Enhanced spin-torque in double-barrier magnetic tunnel junctions by a nonmagnetic-metal spacer,” Appl. Phys. Lett., Vol. 107, pp. 152401. (SCI, Physics, Applied, RF: 28/145=19.3%, IF:3.142)
7. Y. H. Cheng, C. H. Chen, K. Y. Yu, and W. J. Hsueh*, 2015, “Extraordinary light absorptance in graphene superlattices,” Opt. Express, Vol. 23, No. 22, pp. 28755-28760. (SCI, Optics, RF: 14/90=15.6%, IF:3.148)
8. C. H. Chen, C. H. Chang, Y. H. Cheng, and W. J. Hsueh*, 2015, “Ultrahigh tunnel magnetoresistance using an artificial superlattice barrier with copper and aluminum oxide,” Europhys. Lett. Vol. 111, pp. 47005. (SCI, Physics, multidisciplinary, RF: 19/79=24.1%, IF:1.963)
9. C. W. Tsao, Y. H. Cheng and and W. J. Hsueh*, 2015 “High-order microring resonator with perfect transmission using symmetric Fibonacci structures,” Opt. Lett., Vol. 40, No. 18, pp. 4237-4240. (SCI, Optics, RF: 15/90=16.7%, IF:3.040)
10. C. H. Chen, B. S. Chao, and and W. J. Hsueh*, 2015, “Huge magnetoresistance in graphene-based magnetic tunnel junctions with superlattice barriers,” J. Phys. D, Vol. 48, No. 335004, pp. 1-6. (SCI, Physics, Applied, RF: 31/145=21.4%, IF:2.772)
11. C. W. Tsao, Y. H. Cheng and and W. J. Hsueh*, 2015, “Sharp resonance with complete transmission in Thue-Morse microring resonators,” Opt. Express, Vol. 23, No. 10, pp. 13613-13618. (SCI, Optics, RF: 14/90=15.6%, IF:3.148)
12. Y. H. Cheng, C. W. Tsao, C. H. Chen and and W. J. Hsueh*, 2015, “Strong localization of photonics in symmetric Fibonacci superlattices,” J. Phys. D, Vol. 49, No. 295101, pp. 1-8. (SCI, Physics, Applied, RF: 31/145=21.4%, IF:2.772)
13. C. H. Chang, C. H. Chen, C. W. Tsao, and W. J. Hsueh*, 2015, “Superradiant modes in resonant quasi-periodic double-period quantum wells,” Opt. Express, Vol. 23, No. 9, pp. 11946-11951. (SCI, Optics, RF: 14/90=15.6%, IF:3.148)
14. R. Z. Qiu , C. H. Chang, Y. H. Cheng and W. J. Hsueh*, 2015, “Localized persistent spin currents in defect-free quasiperiodic rings with Aharonov-Casher effect,” Phys. Lett. A Vol. 379, pp. 1283-1287. (SCI, Physics, multidisciplinary, RF: 26/79=32.9%, IF:1.677)
15. C. H. Chang, Y. H. Cheng, and W. J. Hsueh*, 2014 “Twin extra high photoluminescence in resonant double-period quantum wells,” Opt. Lett., Vol. 39, No. 23, pp. 6581-6584. (SCI, Optics, RF: 11/87=12.6%, IF:3.292)
16. C. H. Chang, C. W. Tsao, and W. J. Hsueh*, 2014 “Superradiant modes in Fibonacci quantum wells under resonant non-Bragg conditions,” New J. Phys., Vol. 16, No. 113069. (SCI, Physics, multidisciplinary, RF: 10/78=12.8%, IF:3.558 )
17. C. W. Tsao, Y. H. Cheng, and W. J. Hsueh*, 2014, “Localized modes in one-dimensional symmetric Thue-Morse quasicrystals,” Opt. Express, Vol. 22, No. 20, pp. 24378-24383. (SCI, Optics, RF: 10/87=11.5%, IF:3.488)
18. R. Z. Qiu, C. H. Chen, C. W. Tsao, and W. J. Hsueh*, 2014 “High-Q filters with complete transports using quasiperiodic rings with spin-orbit interaction,” AIP Adv. Vol. 4, No. 9, pp. 097102. (SCI, Physics, Applied, RF:76/144=52.8%, IF: 1.524)
19. Y. H. Cheng, C. H. Chang, C. H. Chen, and W. J. Hsueh*, 2014 “Bragg-like interference in one-dimensional double-period quasicrystals,” Phys. Rev. A, Vol. 90, No. 023830. (SCI, Optics, RF:16/87=18.4%, IF: 2.808 )
20. C. H. Chen, R. Z. Qiu, C. H. Chang, and W. J. Hsueh*, 2014 “Strongly localized modes in one-dimensional defect-free magnonic quasicrystals,” AIP Adv. Vol. 4, No. 8, pp. 087102. (SCI, Physics, Applied, RF:76/144=52.8%, IF: 1.524)
21. R. Z. Qiu and W. J. Hsueh*, 2014, “Giant persistent currents in quasiperiodic mesoscopic rings,” Phys. Lett. A Vol. 378, pp. 851-855. (SCI, Physics, multidisciplinary, RF:26/78=33.3%, IF:1.683)
22. C. H. Chen and W. J. Hsueh*, 2014, “Enhancement of tunnel magnetoresistance in magnetic tunnel junction by a superlattice barrier,” Appl. Phys. Lett., Vol. 104, pp. 042405. (SCI, Physics, Applied, RF: 21/144=14.6%, IF:3.302)
23. W. J. Hsueh*, C. H. Chang, and C. T. Lin, 2014, “Exciton photoluminescence in resonant quasiperiodic Thue-Morse quantum wells,” Opt. Lett., Vol. 39, No. 3, pp. 489-492. (SCI, Optics, RF: 11/87=12.6%, IF:3.292)
24. C. M. Chang, M. H. Shiao, D. Chiang, S. W. Huang, C. T. Yang, C. T. Cheng, and W. J. Hsueh*, 2014, “The effects of ICP-RIE etching powers on the etching rate and surface roughness of the sapphire substrate,” J. Nanosci. Nanotechnol., Vol. 14 No. 10, pp. 8074-8078. (SCI, Materials science, multidisciplinary, RF: 134/260=51.5%, IF:1.556)
25. C. W. Tsao, W. J. Hsueh*, C. H. Chang, and Y. H. Cheng, 2013, “Quasi-Bragg conditions in Thue-Morse dielectric multilayers,” Opt. Lett., Vol. 38, No. 22, pp. 4562-4565. (SCI, Optics, RF: 10/83=12.0%, IF:3.179)
26. C. M. Chang, D. Chiang, M. H. Shiao, C. T. Yang, M. J. Huang, C. T. Cheng, and W. J. Hsueh*, 2013, “Dual layer photoresist complimentary lithography applied on sapphire substrate for producing submicron patterns,” Microsystem Technologies, Vol. 19 No. 11, pp1745-1751. (SCI, Engineering, electrical & electronic, RF:151/248=60.9%, IF:0.952)
27. W. J. Hsueh*, C. H. Chen and R. Z. Qiu, 2013, “Perfect transmission of spin waves in a one-dimensional magnonic quasicrystal,” Phys. Lett. A Vol. 377, pp. 1378-1385. (SCI, Physics, multidisciplinary, RF: 28/78=35.9%, IF:1.626)
28. Y. H. Cheng and W. J. Hsueh*, 2013, “High-Q filters with complete transmission by quasiperiodic dielectric multilayers,” Opt. Lett., Vol. 38, No. 18, pp. 3631-3634. (SCI, Optics, RF: 10/83=12.0%, IF:3.179)
29. D. Chiang*, C. M. Chang, S. W. Chen, C. T. Yang, and W. J. Hsueh, 2013, “Physical properties of an oxide photoresist film for submicron pattern lithography,” Thin Solid Films, Vol. 542, pp409-414. (SCI, Materials science, Coatings and films, RF:6/18=33.3%, IF:1.867)
30. W. J. Hsueh*, R. Z. Qiu and C. H. Chen, 2013, “Resonant transport and giant persistent currents in double-asymmetric rings”, Eur. Phys. J. B Vol. 86, pp. 27. (SCI, Physics, condensed matter, RF: 42/67=62.7%, IF:1.463)
31. C. H. Chang, C. H. Chen, and W. J. Hsueh*, 2013, “Strong photoluminescence emission from resonant Fibonacci quantum wells,” Opt. Express, Vol. 21, No. 12, pp. 14656-14661. (SCI, Optics, RF: 6/83=7.2%, IF:3.525)
32. C. M. Chang, M. H. Shiao, D. Chiang, C. T. Yang, M. J. Huang, W. J. Hsueh*, 2013, “Submicron-size patterning on the sapphire substrate prepared by nanosphere lithography and nanoimprint lithography techniques,” Met. Mater. Int., Vol. 19 No. 4, pp. 869-874. (SCI, Metallurgy, Metallurgical Engineering, RF:20/75=26.7%, IF:1.223)
33. W. J. Hsueh*, C. H. Chang, Y. H. Cheng, and S. J. Wun, 2012, “Effective Bragg conditions in a one-dimensional quasicrystal,” Opt. Express, Vol. 20, No. 24, pp. 26618-26623. (SCI, Optics, RF: 5/80=6.3%, IF:3.546)
34. M. H. Shiao, C. M. Chang, S. W. Huang, C. T. Lee, T. C. Wu, W. J. Hsueh, K. J. Ma, D. Chiang, 2012, “The sub-micron hole array in sapphire produced by inductively-coupled plasma reactive ion etching,” J. Nanosci. Nanotechnol., Vol. 12 No. 2, pp1641-1644. (SCI, Materials science, multidisciplinary, RF: 133/241=55.2%, IF:1.149)
35. W. J. Hsueh* and S. J. Wun, 2011, “Simple expressions for the maximum omnidirectional bandgap of bilayer photonic crystals,” Opt. Lett., Vol. 36, No. 9, pp. 1581-1583. (SCI, Optics, RF: 7/79=8.9%, IF:3.399)
36. W. J. Hsueh*, S. J. Wun, Z. J. Lin and Y. H. Cheng, 2011, “Features of the perfect transmission in Thue-Morse dielectric multilayers,” J. Opt. Soc. Am. B Vol. 28, No. 11, pp. 2584-2591. (SCI, Optics, RF: 18/79=22.8%, IF: 2.185)
37. W. J. Hsueh*, S. J. Wun, and C. W. Tsao, 2011, “Branching features of photonic bandgaps in Fibonacci dielectric heterostructures,” Opt. Commun. Vol. 284, No. 7, pp. 1880-1886. (SCI, Optics, RF:37/79=46.8%, IF:1.486)
38. W. J. Hsueh*, R. Z. Qiu and C. W. Wu, 2010, “Fractal property of band branching in Fibonacci mesoscopic rings,” J. Phys. Soc. Jpn. Vol. 79, No. 6, pp. 064704. (SCI, Physics, multidisciplinary, RF: 15/80=18.8%, IF: 2.905)
39. W. J. Hsueh*, C. H. Chen and C. H. Chang, 2010, “Bound states in the continuum in quasiperiodic systems,” Phys. Lett. A. Vol. 374, pp. 4804-4807. (SCI, Physics, multidisciplinary, RF:22/80=27.5%, IF:1.963)
40. W. J. Hsueh*, S. J. Wun and T. H. Yu, 2010, “Characterization of omnidirectional band gaps in multiple frequency ranges of one-dimensional photonic crystals,” J. Opt. Soc. Am. B Vol. 27, No. 5, pp. 1092-1098. (SCI, Optics, RF: 16/78=20.5%, IF: 2.097)
41. W. J. Hsueh*, C. H. Chen, and J. A. Lai, 2010, “Splitting rules of electronic miniband in Fibonacci superlattices: a gap map approach”, Eur. Phys. J. B Vol. 73, pp. 503-508. (SCI, Physics, condensed matter, RF: 29/68=42.6%, IF:1.575 )