From The University of Texas-Austin And Peking University [北京大学](CN) Via “TechXplore” at “Science X”: “The successful integration of a sub-0.5nm dielectric with 2D semiconductors”

From The University of Texas-Austin


Peking University[北京大学](CN)


TechXplore at Science X

Ingrid Fadelli

Synthesis and properties of the single-crystalline native oxide dielectric β-Bi2SeO5. a, Diagram of the UV-assisted intercalative oxidation of 2D Bi2O2Se for single-crystalline native oxide dielectric β-Bi2SeO5. b, Wafer-scale area-selective oxidation for Bi2O2Se/β-Bi2SeO5 heterostructure. c, Atomic structure of Bi2O2Se/β-Bi2SeO5 heterostructure at the intercalative oxidation frontier. d, Comparison of single-crystalline β-Bi2SeO5 and common dielectrics in terms of EOT or ECT (effective capacitance thickness) versus leakage current at 1 V gate voltage. Credit: Zhang et al.

Field-effect transistors (FETs) are transistors in which the resistance of most of the electrical current can be controlled by a transverse electric field. Over the past decade or so, these devices have proved to be very valuable solutions for controlling the flow of current in semiconductors.

To further develop FETs, electronics engineers worldwide have recently been trying to reduce their size. While these down-scaling efforts have been found to increase the device’s speed and lower the power consumption, they are also associated with short-channel effects (i.e., unfavorable effects that occur when an FET’s channel length is approximately equal to the space charge regions of source and drain junctions within its substrate).

These undesirable effects, which include barrier lowering and velocity saturation, could be suppressed by using 2D semiconductor channels with high carrier mobilities and ultrathin high-k dielectrics (i.e., materials with high dielectric constants). Integrating 2D semiconductors with dielectrics with similar oxide thicknesses has been found to be highly challenging.

Researchers at Peking University and University of Texas at Austin have recently demonstrated the successful integration of a sub-0.5nm dielectric layer with 2D semiconductor-based transistors. Their design, introduced in a paper published in Nature Electronics [below], could ultimately pave the way towards the development of smaller, faster, and more efficient FETs.

“Previously [Nature Electronics (below)] we have synthesized a poly-crystalline high-κ (dielectric constant) native oxide dielectric of 2D Bi2O2Se and found that its equivalent oxide thickness (EOT) can be scaled down to 0.9 nm, but the leakage current exceeds the low-power limit,” Hailin Peng, one of the researchers who carried out the study, told TechXplore. “Inspired by the layered crystal structure of 2D Bi2O2Se and the intercalation of 2D materials, we designed an intercalative oxidation process to retain the lattice framework of the precursor, to obtain a single-crystalline native oxide with better insulativity for further downscaling.”

To integrate their dielectric with 2D semiconductors, Peng and his colleagues used a process called UV-assisted intercalative oxidation. Firstly, they decomposed oxygen molecules contained in the air into atomic oxygen using 185 nm ultraviolet (UV) rays emitted from a low-pressure mercury lamp.

Subsequently, they used the atomic oxygen to oxidize the Se2- layer in the 2D semiconductor Bi2O2Se between the two [Bi2O2]n2n+ layers, without affecting the properties of the [Bi2O2]n2n+ layers. This process led to the formation of a new ‘layered phase,” which inherited the single-crystalline [Bi2O2]n2n+ structure of the original Bi2O2Se sample.

“The as-synthesized oxide is further confirmed to be a single-crystalline native dielectric and named β-Bi2SeO5,” Peng explained. “The single-crystalline native oxide β-Bi2SeO5 has a thickness-independent high dielectric constant of about 22, ultraflat lattice-matched interface, and excellent insulativity. Even when scaled down to 2.3 nm and the EOT (equivalent oxide thickness, 3.9×thickness/dielectric constant) is as low as 0.41 nm, the leakage current at 1 V gate voltage is still below the low-power limit (0.015 A/cm2), meeting the industrial requirements of dielectrics in next-generation transistors.”

The initial tests carried out by Peng and his colleagues yielded interesting results. Overall, their findings suggest β-Bi2SeO5, the material they created, could be promising for developing an ultrathin high-κ (dielectric constant) gate dielectric in 2D transistors.

“The most notable achievement of our study was the successful integration of sub-0.5-nm-EOT dielectrics in top-gated 2D transistors, which meets the benchmarks of dielectric in the 2021 International Roadmap for Devices and Systems,” Peng said. “Thus, one of the challenges for 2D electronics, the integration with sub-0.5-nm-EOT ultrathin high-κ dielectric, has been overcome.”

This team of researchers demonstrated the possibility of integrating 2D semiconductors with high-k dielectrics. In the future, the material that they created and the method introduced in their paper could be used to create smaller and highly-performing FETs that are not adversely impacted by short-channel effects.

“We will now further investigate the compatibility of β-Bi2SeO5 with other common 2D materials and metal electrodes,” Peng added. “In addition, a large-scale transfer process of Bi2SeO5 or its precursor Bi2O2Se is also desired for the integration of this ultrathin high-κ dielectric with a broad range of 2D materials.”

Science papers:
Nature Electronics
Nature Electronics (2020)

See the full article here.


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Peking University[北京大学](CN) is a public research university in Beijing, China. The university is funded by the Ministry of Education.

Peking University was established as the Imperial University of Peking in 1898 when it received its royal charter by the Guangxu Emperor. A successor of the older Guozijian Imperial College, the university’s romanized name ‘Peking’ retains the older transliteration of ‘Beijing’ that has been superseded in most other contexts. Perennially ranked as one of the top academic institutions in China and the world, as of 2021 Peking University was ranked 16th globally and 1st in the Asia-Pacific & emerging countries by Times Higher Education, while as of 2022 it was ranked 12th globally and 1st in China by QS World University Rankings.

Throughout its history, Peking University has had an important role “at the center of major intellectual movements” in China. Abolished of its status as a royal institution after the fall of the Qing dynasty and the Xinhai Revolution; from the early 1920s, the university became a center for China’s emerging, progressive, and republican movements. Faculty and students held important roles in originating the New Culture Movement, the May Fourth Movement protests, and other significant cultural and sociopolitical events, to the extent that the university’s history has been closely tied to that of modern China. Peking University has educated and hosted many prominent modern Chinese figures, including Mao Zedong, Lu Xun, Gu Hongming, Hu Shih, Mao Dun, Li Dazhao, Chen Duxiu, and current Premier Li Keqiang.

Peking University is a member of the C9 League, Double First Class University Plan, former Project 985 and former Project 211. The university library contains over 8 million volumes. The university also operates the PKU Hall, a professional performing arts center, and the Arthur M. Sackler Museum of Arts and Archaeology. The university is also renowned for its campus grounds and the beauty of its traditional Chinese architecture. Additionally, it hosts one of the only undergraduate liberal arts colleges in Asia, and is a Class A institution under the Chinese Double First Class University program. Peking University’s staff include 76 members of the Chinese Academy of Sciences, 19 members of the Chinese Academy of Engineering and 25 members of the World Academy of Sciences.

In 2000, Beijing Medical University was merged back into Peking University and became the Peking University Health Science Campus. Beijing Medical University, which used to be Medical School of Peking University, was separated from Peking University in 1952. Peking University now has eight affiliated hospitals and 12 teaching hospitals.

In 2001, Peking University established the Yuanpei Program. It was formalized in 2007 as the Yuanpei College, named in honor of the highly respected former university president Cai Yuanpei. The college hosts an elite undergraduate liberal arts program that allows students to freely choose specializations. In the same year, Peking University set up a satellite campus for graduate students in Shenzhen. The university’s second business school, Peking University HSBC Business School was launched on the Shenzhen campus in 2004.

In 2014, Peking University established the Yenching Academy, a fully funded global fellowship program designed “to cultivate leaders who will advocate for global progress and cultural understanding.”

In October 2015, Peking University alumni Professor Tu Youyou was awarded the Nobel Prize in Physiology or Medicine for her discovery of artemisinin. Having saved millions of lives, artemisinin has made significant contributions to global health in regard to the fight against malaria.

In May 2016, the Peking University Department of Psychology was renamed as Peking University School of Psychological and Cognitive Sciences. On July 5, Peking University and Moscow State University signed the Joint Declaration on the Establishment of the Comprehensive University Alliance between the People’s Republic of China and the Russian Federation, proposing the establishment of the China-Russia Comprehensive University Alliance. On August 29, Peking University signed a memorandum with the Shenzhen Municipal People’s Government to jointly open Peking University Shenzhen Campus. On September 20, Peking University Institute of Humanities and Social Sciences was officially inaugurated.

On February 20, 2017, the University officially signed a contract with the British Open University to establish the Oxford Campus of Peking University HSBC Business School, Peking University Oxford Center and Shenzhen Oxford Innovation Center. In March, the National Engineering Laboratory for Big Data Analysis and Application Technology was unveiled. In September, Peking University was selected as a national “double first-class” university. On December 13, Peking University School of Advanced Agricultural Sciences was established.

On May 4, 2018, Peking University held its 120th anniversary meeting at the Khoo Teck Puat Gymnasium. On October 24th, Peking University led the formation of the medical “Double First-Class” (i.e. world-class universities and first-class disciplines) Construction Alliance, which is the first unofficial non-profit medical higher education and medical discipline construction collaboration organization.

In February 2019, Peking University and the University of Hong Kong signed a cooperation agreement to cooperate in the dual bachelor’s degree program in law; in the same month, Peking University and the Chinese University of Hong Kong signed a cooperation agreement to jointly organize undergraduate double-degree programs of Linguistics and Chinese Language and Literature. In December, it joined the “Belt and Road” Think Tank Cooperation Alliance as a governing unit.

In May 2019, Peking University and Beijing Geely University signed an agreement. Peking University will build a new campus on the original site of Geely Institute in Changping.

Several rankings have placed Peking University among the top universities in mainland China. In 2015, the Chinese University Alumni Association in partnership with China Education Center considered it first among all Chinese universities.

Typically, Peking University is consistently ranked among the top universities in the Asia-Pacific and the world according to major international university rankings. The joint THE-QS World University Rankings 2006 ranked Peking University 1st in the Asia & Oceania region and 14th in the world. In 2014, the U.S. News & World Report ranked Peking University 39th in the world, 2nd in the Asia-Pacific and 1st in China. Peking had topped the newly launched Times Higher Education BRICS & Emerging Economies since its inception in 2014.

The 2023 QS World University Rankings ranked Peking University 12th in the world , 2nd in Asia and first in China. As of 2022, the Times Higher Education World University Rankings ranked Peking University 16th in the world and 1st in China & the Asia-Pacific, with its teaching and research performance indicators placed at 4th and 9th in the world respectively. Peking University was also ranked 15th in the world and 1st in the Asia-Pacific in The Three University Missions Ranking. Academic Ranking of World Universities, also known as the Shanghai Ranking, placed Peking University 34th in the world, 3rd in Asia, and 2nd in China. The U.S. News & World Report ranked Peking University 45th in the world, 5th in Asia and 2nd in China.

In the QS Graduate Employability Rankings 2017, an annual ranking of university graduates’ employability, Peking University was ranked 11th in the world and 2nd in Asia. In 2019, the QS World University Rankings ranked the university as one of the world’s top 20 universities for academic reputation where, it ranked 16 globally, and top 10 in the world and first in the Asia-Pacific for employer reputation. Since 2017, Peking has been placed among the world’s top 20 most reputable universities by the Times Higher Education World Reputation Rankings, where it ranked 15 globally in 2021.

Research Performance and Subjects Rankings

The 2020 CWTS Leiden Ranking ranked Peking University at 8th in the world based on their publications for the time period 2015–2018. For the high quality of research in natural science and life science, Peking University ranked 10th among the leading institutions, and 6th among the leading universities globally in the Nature Index 2022 Annual Tables by Nature Research. In 2020, it ranked 13th among the universities around the world by SCImago Institutions Rankings.

As of 2021, it was ranked 8th globally in “Education”, 12th in “Engineering and Technology”, 15th in “Physical Science”, 17th in “Computer Science”, 18th in “Social Science”, 19th in “Life Science”, 21st in “Arts and Humanities”, 22nd in “Business and Economics”, 22nd in “Clinical, pre-clinical and Health” and 45th in “Psychology” by the Times Higher Education Rankings by Subjects.

University of Texas-Austin

University of Texas-Austin campus

The University of Texas-Austin is a public research university in Austin, Texas and the flagship institution of the University of Texas System. Founded in 1883, the University of Texas was inducted into the Association of American Universities in 1929, becoming only the third university in the American South to be elected. The institution has the nation’s seventh-largest single-campus enrollment, with over 50,000 undergraduate and graduate students and over 24,000 faculty and staff.

A Public Ivy, it is a major center for academic research. The university houses seven museums and seventeen libraries, including the LBJ Presidential Library and the Blanton Museum of Art, and operates various auxiliary research facilities, such as the J. J. Pickle Research Campus and the McDonald Observatory. As of November 2020, 13 Nobel Prize winners, four Pulitzer Prize winners, two Turing Award winners, two Fields medalists, two Wolf Prize winners, and two Abel prize winners have been affiliated with the school as alumni, faculty members or researchers. The university has also been affiliated with three Primetime Emmy Award winners, and has produced a total of 143 Olympic medalists.

Student-athletes compete as the Texas Longhorns and are members of the Big 12 Conference. Its Longhorn Network is the only sports network featuring the college sports of a single university. The Longhorns have won four NCAA Division I National Football Championships, six NCAA Division I National Baseball Championships, thirteen NCAA Division I National Men’s Swimming and Diving Championships, and has claimed more titles in men’s and women’s sports than any other school in the Big 12 since the league was founded in 1996.


The first mention of a public university in Texas can be traced to the 1827 constitution for the Mexican state of Coahuila y Tejas. Although Title 6, Article 217 of the Constitution promised to establish public education in the arts and sciences, no action was taken by the Mexican government. After Texas obtained its independence from Mexico in 1836, the Texas Congress adopted the Constitution of the Republic, which, under Section 5 of its General Provisions, stated “It shall be the duty of Congress, as soon as circumstances will permit, to provide, by law, a general system of education.”

On April 18, 1838, “An Act to Establish the University of Texas” was referred to a special committee of the Texas Congress, but was not reported back for further action. On January 26, 1839, the Texas Congress agreed to set aside fifty leagues of land—approximately 288,000 acres (117,000 ha)—towards the establishment of a publicly funded university. In addition, 40 acres (16 ha) in the new capital of Austin were reserved and designated “College Hill”. (The term “Forty Acres” is colloquially used to refer to the University as a whole. The original 40 acres is the area from Guadalupe to Speedway and 21st Street to 24th Street.)

In 1845, Texas was annexed into the United States. The state’s Constitution of 1845 failed to mention higher education. On February 11, 1858, the Seventh Texas Legislature approved O.B. 102, an act to establish the University of Texas, which set aside $100,000 in United States bonds toward construction of the state’s first publicly funded university (the $100,000 was an allocation from the $10 million the state received pursuant to the Compromise of 1850 and Texas’s relinquishing claims to lands outside its present boundaries). The legislature also designated land reserved for the encouragement of railroad construction toward the university’s endowment. On January 31, 1860, the state legislature, wanting to avoid raising taxes, passed an act authorizing the money set aside for the University of Texas to be used for frontier defense in west Texas to protect settlers from Indian attacks.

Texas’s secession from the Union and the American Civil War delayed repayment of the borrowed monies. At the end of the Civil War in 1865, The University of Texas’s endowment was just over $16,000 in warrants and nothing substantive had been done to organize the university’s operations. This effort to establish a University was again mandated by Article 7, Section 10 of the Texas Constitution of 1876 which directed the legislature to “establish, organize and provide for the maintenance, support and direction of a university of the first class, to be located by a vote of the people of this State, and styled “The University of Texas”.

Additionally, Article 7, Section 11 of the 1876 Constitution established the Permanent University Fund, a sovereign wealth fund managed by the Board of Regents of the University of Texas and dedicated to the maintenance of the university. Because some state legislators perceived an extravagance in the construction of academic buildings of other universities, Article 7, Section 14 of the Constitution expressly prohibited the legislature from using the state’s general revenue to fund construction of university buildings. Funds for constructing university buildings had to come from the university’s endowment or from private gifts to the university, but the university’s operating expenses could come from the state’s general revenues.

The 1876 Constitution also revoked the endowment of the railroad lands of the Act of 1858, but dedicated 1,000,000 acres (400,000 ha) of land, along with other property appropriated for the university, to the Permanent University Fund. This was greatly to the detriment of the university as the lands the Constitution of 1876 granted the university represented less than 5% of the value of the lands granted to the university under the Act of 1858 (the lands close to the railroads were quite valuable, while the lands granted the university were in far west Texas, distant from sources of transportation and water). The more valuable lands reverted to the fund to support general education in the state (the Special School Fund).

On April 10, 1883, the legislature supplemented the Permanent University Fund with another 1,000,000 acres (400,000 ha) of land in west Texas granted to the Texas and Pacific Railroad but returned to the state as seemingly too worthless to even survey. The legislature additionally appropriated $256,272.57 to repay the funds taken from the university in 1860 to pay for frontier defense and for transfers to the state’s General Fund in 1861 and 1862. The 1883 grant of land increased the land in the Permanent University Fund to almost 2.2 million acres. Under the Act of 1858, the university was entitled to just over 1,000 acres (400 ha) of land for every mile of railroad built in the state. Had the 1876 Constitution not revoked the original 1858 grant of land, by 1883, the university lands would have totaled 3.2 million acres, so the 1883 grant was to restore lands taken from the university by the 1876 Constitution, not an act of munificence.

On March 30, 1881, the legislature set forth the university’s structure and organization and called for an election to establish its location. By popular election on September 6, 1881, Austin (with 30,913 votes) was chosen as the site. Galveston, having come in second in the election (with 20,741 votes), was designated the location of the medical department (Houston was third with 12,586 votes). On November 17, 1882, on the original “College Hill,” an official ceremony commemorated the laying of the cornerstone of the Old Main building. University President Ashbel Smith, presiding over the ceremony, prophetically proclaimed “Texas holds embedded in its earth rocks and minerals which now lie idle because unknown, resources of incalculable industrial utility, of wealth and power. Smite the earth, smite the rocks with the rod of knowledge and fountains of unstinted wealth will gush forth.” The University of Texas officially opened its doors on September 15, 1883.

Expansion and growth

In 1890, George Washington Brackenridge donated $18,000 for the construction of a three-story brick mess hall known as Brackenridge Hall (affectionately known as “B.Hall”), one of the university’s most storied buildings and one that played an important place in university life until its demolition in 1952.

The old Victorian-Gothic Main Building served as the central point of the campus’s 40-acre (16 ha) site, and was used for nearly all purposes. But by the 1930s, discussions arose about the need for new library space, and the Main Building was razed in 1934 over the objections of many students and faculty. The modern-day tower and Main Building were constructed in its place.

In 1910, George Washington Brackenridge again displayed his philanthropy, this time donating 500 acres (200 ha) on the Colorado River to the university. A vote by the regents to move the campus to the donated land was met with outrage, and the land has only been used for auxiliary purposes such as graduate student housing. Part of the tract was sold in the late-1990s for luxury housing, and there are controversial proposals to sell the remainder of the tract. The Brackenridge Field Laboratory was established on 82 acres (33 ha) of the land in 1967.

In 1916, Gov. James E. Ferguson became involved in a serious quarrel with the University of Texas. The controversy grew out of the board of regents’ refusal to remove certain faculty members whom the governor found objectionable. When Ferguson found he could not have his way, he vetoed practically the entire appropriation for the university. Without sufficient funding, the university would have been forced to close its doors. In the middle of the controversy, Ferguson’s critics brought to light a number of irregularities on the part of the governor. Eventually, the Texas House of Representatives prepared 21 charges against Ferguson, and the Senate convicted him on 10 of them, including misapplication of public funds and receiving $156,000 from an unnamed source. The Texas Senate removed Ferguson as governor and declared him ineligible to hold office.

In 1921, the legislature appropriated $1.35 million for the purchase of land next to the main campus. However, expansion was hampered by the restriction against using state revenues to fund construction of university buildings as set forth in Article 7, Section 14 of the Constitution. With the completion of Santa Rita No. 1 well and the discovery of oil on university-owned lands in 1923, the university added significantly to its Permanent University Fund. The additional income from Permanent University Fund investments allowed for bond issues in 1931 and 1947, which allowed the legislature to address funding for the university along with the Agricultural and Mechanical College (now known as Texas A&M University). With sufficient funds to finance construction on both campuses, on April 8, 1931, the Forty Second Legislature passed H.B. 368. which dedicated the Agricultural and Mechanical College a 1/3 interest in the Available University Fund, the annual income from Permanent University Fund investments.

The University of Texas was inducted into The Association of American Universities in 1929. During World War II, the University of Texas was one of 131 colleges and universities nationally that took part in the V-12 Navy College Training Program which offered students a path to a Navy commission.

In 1950, following Sweatt v. Painter, the University of Texas was the first major university in the South to accept an African-American student. John S. Chase went on to become the first licensed African-American architect in Texas.

In the fall of 1956, the first black students entered the university’s undergraduate class. Black students were permitted to live in campus dorms, but were barred from campus cafeterias. The University of Texas integrated its facilities and desegregated its dorms in 1965. UT, which had had an open admissions policy, adopted standardized testing for admissions in the mid-1950s at least in part as a conscious strategy to minimize the number of Black undergraduates, given that they were no longer able to simply bar their entry after the Brown decision.

Following growth in enrollment after World War II, the university unveiled an ambitious master plan in 1960 designed for “10 years of growth” that was intended to “boost the University of Texas into the ranks of the top state universities in the nation.” In 1965, the Texas Legislature granted the university Board of Regents to use eminent domain to purchase additional properties surrounding the original 40 acres (160,000 m^2). The university began buying parcels of land to the north, south, and east of the existing campus, particularly in the Blackland neighborhood to the east and the Brackenridge tract to the southeast, in hopes of using the land to relocate the university’s intramural fields, baseball field, tennis courts, and parking lots.

On March 6, 1967, the Sixtieth Texas Legislature changed the university’s official name from “The University of Texas” to “The University of Texas at Austin” to reflect the growth of the University of Texas System.

Recent history

The first presidential library on a university campus was dedicated on May 22, 1971, with former President Johnson, Lady Bird Johnson and then-President Richard Nixon in attendance. Constructed on the eastern side of the main campus, the Lyndon Baines Johnson Library and Museum is one of 13 presidential libraries administered by the National Archives and Records Administration.

A statue of Martin Luther King Jr. was unveiled on campus in 1999 and subsequently vandalized. By 2004, John Butler, a professor at the McCombs School of Business suggested moving it to Morehouse College, a historically black college, “a place where he is loved”.

The University of Texas-Austin has experienced a wave of new construction recently with several significant buildings. On April 30, 2006, the school opened the Blanton Museum of Art. In August 2008, the AT&T Executive Education and Conference Center opened, with the hotel and conference center forming part of a new gateway to the university. Also in 2008, Darrell K Royal-Texas Memorial Stadium was expanded to a seating capacity of 100,119, making it the largest stadium (by capacity) in the state of Texas at the time.

On January 19, 2011, the university announced the creation of a 24-hour television network in partnership with ESPN, dubbed the Longhorn Network. ESPN agreed to pay a $300 million guaranteed rights fee over 20 years to the university and to IMG College, the school’s multimedia rights partner. The network covers the university’s intercollegiate athletics, music, cultural arts, and academics programs. The channel first aired in September 2011.