Tagged: Diamond is the hardest material in nature. But out of many expectations it also has great potential as an excellent electronic material. Toggle Comment Threads | Keyboard Shortcuts

  • richardmitnick 4:16 pm on April 8, 2021 Permalink | Reply
    Tags: , , , , Diamond is the hardest material in nature. But out of many expectations it also has great potential as an excellent electronic material., Diamonds as prime candidates for advanced functional devices in microelectronics; photonics; and quantum information technologies, Microfabricated diamonds, , Next-generation microelectronics, , The first time showing the extremely large uniform elasticity of diamond by tensile experiments.   

    From City University of Hong Kong [香港城市大學] (HK): “Stretching diamond for next-generation microelectronics” 

    From City University of Hong Kong [香港城市大學] (HK)

    01 Jan 2021 [Just now in social media. What woke them up?]

    Office of the Vice-President (Research & Technology)
    City University of Hong Kong
    Tel +852 3442-6847
    Fax +852 3442-0322
    vprt@cityu.edu.hk

    1
    Stretching of microfabricated diamonds pave ways for applications in next-generation microelectronics. Credit: Dang Chaoqun / City University of Hong Kong.

    Diamond is the hardest material in nature. But out of many expectations it also has great potential as an excellent electronic material. A joint research team led by City University of Hong Kong (CityU) has demonstrated for the first time the large, uniform tensile elastic straining of microfabricated diamond arrays through the nanomechanical approach. Their findings have shown the potential of strained diamonds as prime candidates for advanced functional devices in microelectronics; photonics; and quantum information technologies.

    The research was co-led by Dr Lu Yang, Associate Professor in the Department of Mechanical Engineering (MNE) at CityU and researchers from Massachusetts Institute of Technology(US) and Harbin Institute of Technology [哈尔滨工业大学] (CN). Their findings have been recently published in the prestigious scientific journal Science, titled “Achieving large uniform tensile elasticity in microfabricated diamond”.

    “This is the first time showing the extremely large uniform elasticity of diamond by tensile experiments. Our findings demonstrate the possibility of developing electronic devices through ‘deep elastic strain engineering’ of microfabricated diamond structures,” said Dr Lu.

    2
    Diamond: “Mount Everest” of electronic materials.

    Well known for its hardness, industrial applications of diamonds are usually cutting, drilling, or grinding. But diamond is also considered as a high-performance electronic and photonic material due to its ultra-high thermal conductivity, exceptional electric charge carrier mobility, high breakdown strength and ultra-wide bandgap. Bandgap is a key property in semi-conductor, and wide bandgap allows operation of high-power or high-frequency devices. “That’s why diamond can be considered as ‘Mount Everest’ of electronic materials, possessing all these excellent properties,” Dr Lu said.

    However, the large bandgap and tight crystal structure of diamond make it difficult to “dope”, a common way to modulate the semi-conductors’ electronic properties during production, hence hampering the diamond’s industrial application in electronic and optoelectronic devices. A potential alternative is by “strain engineering”, that is to apply very large lattice strain, to change the electronic band structure and associated functional properties. But it was considered as “impossible” for diamond due to its extremely high hardness.

    Then in 2018, Dr Lu and his collaborators discovered that, surprisingly, nanoscale diamond can be elastically bent with unexpected large local strain. This discovery suggests the change of physical properties in diamond through elastic strain engineering can be possible. Based on this, the latest study showed how this phenomenon can be utilized for developing functional diamond devices.

    Uniform tensile straining across the sample

    3
    Fig2: Illustration of tensile straining of microfabricated diamond bridge samples. Credit: Dang Chaoqun / City University of Hong Kong.

    The team firstly microfabricated single-crystalline diamond samples from a solid diamond single crystals. The samples were in bridge-like shape – about one micrometre long and 300 nanometres wide, with both ends wider for gripping (see Fig. 2).

    The diamond bridges were then uniaxially stretched in a well-controlled manner within an electron microscope. Under cycles of continuous and controllable loading-unloading of quantitative tensile tests, the diamond bridges demonstrated a highly uniform, large elastic deformation of about 7.5% strain across the whole gauge section of the specimen, rather than deforming at a localized area in bending. And they recovered their original shape after unloading.

    By further optimizing the sample geometry using the American Society for Testing and Materials (ASTM) standard, they achieved a maximum uniform tensile strain of up to 9.7%, which even surpassed the maximum local value in the 2018 study, and was close to the theoretical elastic limit of diamond. More importantly, to demonstrate the strained diamond device concept, the team also realized elastic straining of microfabricated diamond arrays.

    Tuning the bandgap by elastic strains

    The team then performed density functional theory (DFT) calculations to estimate the impact of elastic straining from 0 to 12% on the diamond’s electronic properties. The simulation results indicated that the bandgap of diamond generally decreased as the tensile strain increased, with the largest bandgap reduction rate down from about 5 eV to 3 eV at around 9% strain along a specific crystalline orientation. The team performed an electron energy-loss spectroscopy analysis on a pre-strained diamond sample and verified this bandgap decreasing trend.

    Their calculation results also showed that, interestingly, the bandgap could change from indirect to direct with the tensile strains larger than 9% along another crystalline orientation. Direct bandgap in semi-conductor means an electron can directly emit a photon, allowing many optoelectronic applications with higher efficiency.

    These findings are an early step in achieving deep elastic strain engineering of microfabricated diamonds. By nanomechanical approach, the team demonstrated that the diamond’s band structure can be changed, and more importantly, these changes can be continuous and reversible, allowing different applications, from micro/nanoelectromechanical systems (MEMS/NEMS), strain-engineered transistors, to novel optoelectronic and quantum technologies. “I believe a new era for diamond is ahead of us,” said Dr Lu.

    Dr Lu, Dr Alice Hu, who is also from MNE at CityU, Professor Li Ju from Massachusetts Institute of Technology(US) and Professor Zhu Jiaqi from HIT are the corresponding authors of the paper. The co-first authors are Dang Chaoqun, PhD graduate, and Dr Chou Jyh-Pin, former postdoctoral fellow from MNE at CityU, Dr Dai Bing from HIT, and Chou Chang-Ti from National Chiao Tung University [國立交通大學] (CN). Dr Fan Rong and Lin Weitong from CityU are also part of the team. Other collaborating researchers are from the DOE’s Lawrence Berkeley National Laboratory (US), University of California, Berkeley (US), and Southern University of Science and Technology [南方科技大學](CN).

    The research at CityU was funded by the Hong Kong Research Grants Council and the National Natural Science Foundation of China.

    See the full article here.

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    City University of Hong Kong [香港城市大學](HK)(CityU) is a public research university in Kowloon, Hong Kong. It was founded in 1984 as City Polytechnic of Hong Kong and became a fully accredited university in 1994.

    The university has nine main schools offering courses in business, science, engineering, liberal art, social sciences, law and Veterinary Medicine, along with Chow Yei Ching School of Graduate Studies, CityU Shenzhen Research Institute, and Hong Kong Institute for Advanced Study.

    City University’s origins lie in the calls for a “second polytechnic” in the years following the 1972 establishment of the Hong Kong Polytechnic. In 1982, Executive Council member Chung Sze-yuen spoke of a general consensus that “a second polytechnic of similar size to the first should be built as soon as possible.” District administrators from Tuen Mun and Tsuen Wan lobbied the government to build the new institution in their respective new towns. The government instead purchased temporary premises at the new Argyle Centre Tower II in Mong Kok, a property developed by the Mass Transit Railway Corporation in concert with the then-Argyle Station. The new school was called City Polytechnic of Hong Kong, a name chosen among nearly 300 suggestions made by members of the public.

    The new polytechnic opened on 8 October 1984, welcoming 480 full-time and 680 part-time students. The provision for part-time students contributed to high enrolment, with the quota being filled almost immediately.

    The architectural contract to design the new campus was won by Percy Thomas Partnership in association with Alan Fitch and W.N. Chung. It was originally slated to open by October 1988. The first phase was officially opened by Governor Wilson on 15 January 1990, and boasted 14 lecture theatres and 1,500 computers. By 1991, the school had over 8,000 full-time students and approximately 3,000 part-time students. The second phase of the permanent campus opened 1993. The school achieved university status in 1994 and the name was changed accordingly.

    In April 2015 the university abruptly and controversially shut down its MFA programme in creative writing. Students and alumni launched a petition against the decision, while the faculty and noted international writers issued an open letter questioning the reasoning behind the closure. Acclaimed Canadian novelist and faculty member Madeleine Thien, writing in The Guardian, was among those who attributed the decision to censorship and diminishing freedom of expression in Hong Kong.

     
  • richardmitnick 2:33 pm on December 31, 2020 Permalink | Reply
    Tags: , , , , Deep elastic strain engineering, , Diamond is the hardest material in nature. But out of many expectations it also has great potential as an excellent electronic material., Nanoscale diamond can be elastically bent with unexpected large local strain., , , Strained diamonds as prime candidates for advanced functional devices in microelectronics; photonics; and quantum information technologies.   

    From City University of Hong Kong [香港城市大學] (HK): “Stretching diamond for next-generation microelectronics” 

    From City University of Hong Kong [香港城市大學] (HK)

    01 Jan 2021
    Office of the Vice-President (Research & Technology)
    5107, 5/F, Cheng Yick-chi Building, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon Tong, Kowloon, Hong Kong SAR
    Tel:+852 3442-6847
    Fax: +852 3442-0322
    vprt@cityu.edu.hk

    1
    Fig: Stretching of microfabricated diamonds pave ways for applications in next-generation microelectronics. (Credit: Dang Chaoqun / City University of Hong Kong.

    Diamond is the hardest material in nature. But out of many expectations, it also has great potential as an excellent electronic material. A joint research team led by City University of Hong Kong (CityU) has demonstrated for the first time the large, uniform tensile elastic straining of microfabricated diamond arrays through the nanomechanical approach. Their findings have shown the potential of strained diamonds as prime candidates for advanced functional devices in microelectronics, photonics, and quantum information technologies.

    The research was co-led by Dr Lu Yang, Associate Professor in the Department of Mechanical Engineering (MNE) at CityU and researchers from Massachusetts Institute of Technology (MIT) and Harbin Institute of Technology (HIT). Their findings have been recently published in the prestigious scientific journal Science, titled Achieving large uniform tensile elasticity in microfabricated diamond.

    “This is the first time showing the extremely large, uniform elasticity of diamond by tensile experiments. Our findings demonstrate the possibility of developing electronic devices through ‘deep elastic strain engineering’ of microfabricated diamond structures,” said Dr Lu.

    Diamond: “Mount Everest” of electronic materials

    Well known for its hardness, industrial applications of diamonds are usually cutting, drilling, or grinding. But diamond is also considered as a high-performance electronic and photonic material due to its ultra-high thermal conductivity, exceptional electric charge carrier mobility, high breakdown strength and ultra-wide bandgap. Bandgap is a key property in semi-conductor, and wide bandgap allows operation of high-power or high-frequency devices. “That’s why diamond can be considered as ‘Mount Everest’ of electronic materials, possessing all these excellent properties,” Dr Lu said.

    However, the large bandgap and tight crystal structure of diamond make it difficult to “dope”, a common way to modulate the semi-conductors’ electronic properties during production, hence hampering the diamond’s industrial application in electronic and optoelectronic devices. A potential alternative is by “strain engineering”, that is to apply very large lattice strain, to change the electronic band structure and associated functional properties. But it was considered as “impossible” for diamond due to its extremely high hardness.

    Then in 2018, Dr Lu and his collaborators discovered that, surprisingly, nanoscale diamond can be elastically bent with unexpected large local strain. This discovery suggests the change of physical properties in diamond through elastic strain engineering can be possible. Based on this, the latest study showed how this phenomenon can be utilized for developing functional diamond devices.

    2
    Fig2: Illustration of tensile straining of microfabricated diamond bridge samples. Credit: Dang Chaoqun / City University of Hong Kong.

    Uniform tensile straining across the sample

    The team firstly microfabricated single-crystalline diamond samples from a solid diamond single crystals. The samples were in bridge-like shape – about one micrometre long and 300 nanometres wide, with both ends wider for gripping (see Fig. 2). The diamond bridges were then uniaxially stretched in a well-controlled manner within an electron microscope. Under cycles of continuous and controllable loading-unloading of quantitative tensile tests, the diamond bridges demonstrated a highly uniform, large elastic deformation of about 7.5% strain across the whole gauge section of the specimen, rather than deforming at a localized area in bending. And they recovered their original shape after unloading.

    By further optimizing the sample geometry using the American Society for Testing and Materials (ASTM) standard, they achieved a maximum uniform tensile strain of up to 9.7%, which even surpassed the maximum local value in the 2018 study, and was close to the theoretical elastic limit of diamond. More importantly, to demonstrate the strained diamond device concept, the team also realized elastic straining of microfabricated diamond arrays.

    Tuning the bandgap by elastic strains

    The team then performed density functional theory (DFT) calculations to estimate the impact of elastic straining from 0 to 12% on the diamond’s electronic properties. The simulation results indicated that the bandgap of diamond generally decreased as the tensile strain increased, with the largest bandgap reduction rate down from about 5 eV to 3 eV at around 9% strain along a specific crystalline orientation. The team performed an electron energy-loss spectroscopy analysis on a pre-strained diamond sample and verified this bandgap decreasing trend.

    Their calculation results also showed that, interestingly, the bandgap could change from indirect to direct with the tensile strains larger than 9% along another crystalline orientation. Direct bandgap in semi-conductor means an electron can directly emit a photon, allowing many optoelectronic applications with higher efficiency.

    These findings are an early step in achieving deep elastic strain engineering of microfabricated diamonds. By nanomechanical approach, the team demonstrated that the diamond’s band structure can be changed, and more importantly, these changes can be continuous and reversible, allowing different applications, from micro/nanoelectromechanical systems (MEMS/NEMS), strain-engineered transistors, to novel optoelectronic and quantum technologies. “I believe a new era for diamond is ahead of us,” said Dr Lu.

    Dr Lu, Dr Alice Hu, who is also from MNE at CityU, Professor Li Ju from MIT and Professor Zhu Jiaqi from HIT are the corresponding authors of the paper. The co-first authors are Dang Chaoqun, PhD graduate, and Dr Chou Jyh-Pin, former postdoctoral fellow from MNE at CityU, Dr Dai Bing from HIT, and Chou Chang-Ti from National Chiao Tung University. Dr Fan Rong and Lin Weitong from CityU are also part of the team. Other collaborating researchers are from the Lawrence Berkeley National Laboratory, University of California, Berkeley, and Southern University of Science and Technology.

    The research at CityU was funded by the Hong Kong Research Grants Council and the National Natural Science Foundation of China.

    See the full article here.

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    City University of Hong Kong [香港城市大學](HK)(CityU) is a public research university in Kowloon, Hong Kong. It was founded in 1984 as City Polytechnic of Hong Kong and became a fully accredited university in 1994.

    The university has nine main schools offering courses in business, science, engineering, liberal art, social sciences, law and Veterinary Medicine, along with Chow Yei Ching School of Graduate Studies, CityU Shenzhen Research Institute, and Hong Kong Institute for Advanced Study.

    City University’s origins lie in the calls for a “second polytechnic” in the years following the 1972 establishment of the Hong Kong Polytechnic. In 1982, Executive Council member Chung Sze-yuen spoke of a general consensus that “a second polytechnic of similar size to the first should be built as soon as possible.” District administrators from Tuen Mun and Tsuen Wan lobbied the government to build the new institution in their respective new towns. The government instead purchased temporary premises at the new Argyle Centre Tower II in Mong Kok, a property developed by the Mass Transit Railway Corporation in concert with the then-Argyle Station. The new school was called City Polytechnic of Hong Kong, a name chosen among nearly 300 suggestions made by members of the public.

    The new polytechnic opened on 8 October 1984, welcoming 480 full-time and 680 part-time students. The provision for part-time students contributed to high enrolment, with the quota being filled almost immediately.

    The architectural contract to design the new campus was won by Percy Thomas Partnership in association with Alan Fitch and W.N. Chung. It was originally slated to open by October 1988. The first phase was officially opened by Governor Wilson on 15 January 1990, and boasted 14 lecture theatres and 1,500 computers. By 1991, the school had over 8,000 full-time students and approximately 3,000 part-time students. The second phase of the permanent campus opened 1993. The school achieved university status in 1994 and the name was changed accordingly.

    In April 2015 the university abruptly and controversially shut down its MFA programme in creative writing. Students and alumni launched a petition against the decision, while the faculty and noted international writers issued an open letter questioning the reasoning behind the closure. Acclaimed Canadian novelist and faculty member Madeleine Thien, writing in The Guardian, was among those who attributed the decision to censorship and diminishing freedom of expression in Hong Kong.

     
c
Compose new post
j
Next post/Next comment
k
Previous post/Previous comment
r
Reply
e
Edit
o
Show/Hide comments
t
Go to top
l
Go to login
h
Show/Hide help
shift + esc
Cancel
%d bloggers like this: