Dear Kaisan Muhammad Usman,

Thank you for reply. Indeed ionic properties and transport in smeicodnuctors or band structure materials, e.g. insulators, have created new generation energy devices and tehcnologies as well as new fundamental and science emerging. In my recent academic report form Pakistan several international confs. and seminars, I have presented Semiconductor-Ioncis: Materials and Applications, which has attracted strong attentions and made great impacts on audience, see attached report. However, to establish Semiconductor-Ioncis, the energy band and electron-ion internation, coupling mobilities and mechanisms on how they move and transport together are core fundamentals and new scientific subject which demand professions from semiconductor field reserachers and scientisists like you and others. I am looking for....

Actually, ionic transport in semi conducting materials is an interesting area worth investigating. The popularly known electron mobility and hole mobility have played a vital role in the semiconductors application. The doping of group iv elements with group iii and group v elements to form p-type or n-type semiconductors and the formation of PNP /NPN junction has changed the electronics phase over decades in an affirmative manner. This principle led to the invention of diodes, triodes, bipolar junction transistors and Zena diodes.

However, it is very critical to go beyond electron and hole mobility to a more advanced ionic mobility. This I believe will define the future of electronics engineering as well as the semiconductors in the nearest world.

Dear Kaisan Muhammad Usman,

Thank you for reply. Indeed ionic properties and transport in smeicodnuctors or band structure materials, e.g. insulators, have created new generation energy devices and tehcnologies as well as new fundamental and science emerging. In my recent academic report form Pakistan several international confs. and seminars, I have presented Semiconductor-Ioncis: Materials and Applications, which has attracted strong attentions and made great impacts on audience, see attached report. However, to establish Semiconductor-Ioncis, the energy band and electron-ion internation, coupling mobilities and mechanisms on how they move and transport together are core fundamentals and new scientific subject which demand professions from semiconductor field reserachers and scientisists like you and others. I am looking for....

Dear Bin and Kaisan,

welcome

This topic is very interesting as can extend the electronic devices specially in the applications of energy generation and storage.

I think such high speed solid state ionic conductors are a special case or an extreme case of ionic conduction in electrolytes. One can say that the ions move in such ionic conducting material as if they move in a liquid electrolyte. Therefore they are sometimes called solid electrolytes.

In general the phenomenon of ionic conduction is observed in insulators such as SIO2. In the evolution history of the MOSFETs, one of the main obstacles is to avoid the Na+ ions in the oxide as they drifted under the electric field and caused the shift of the threshold voltage of the transistor with time. In electrochemical devices such as batteries and fuel cells, it is required to use solid electrolytes instead of the liquid electrolytes to ease the device construction. Also, there is the DSSCs which has an electrolyte transport layer. I think ionic conductors are required when we want to transport material other wise if we want to transport charges the electrons will be more suitable because of their much higher mobility.

In order to move ions in a materials these ions must be weakly bound,.Not only that they have to change their position easily in the material which means smaller activation energy for the movement. May be this can be facilitated by the presence of a continuous network of vacancies to avoid the high impediment of the ions. One uses also small ions that can facilitate the motion of ions inside the material.

I think one has to investigate the atomic arrangement of the materials. I t may have profound effect on movement of the ions.

Yes i agree with you more research efforts are required to engineer such materials for high ionic mobility.

Best wishes

Dear Prof. Abdelhalim Zekry,

Thank you very much for informative and deep understanding on topic. I truely appreciate. Just additional comments from my side to consider this research frontier and challenge. My background comes from superionic or fast ionic conductor or solid electrolyte focusing on fuel cell and solid state battery research about 30 years.

Over hundred years, people have looked for and designed ionic conductors/conductivity only focusing on ionic materials or conductors, but challenge unsolved. Typically, in solid oxide fuel cell (SOFC), yttrium stabilized zirconium (YSZ) as the oxide-ionic conducting electrolyte needs high temperature over 700 °C to operate properly because of its insufficient ionic conductivity at lower temperatures. The YSZ has dominated the SOFC technology over hundred years, not yet commercially. Scientific literature increasingly provide evidences that semiconductor-ionic heterostructural materials strongly enhance ionic conductivity. For example, YSZ/SrTiO3 showed significant enhancement of the ionic conductivity compared to pure YSZ.(1-2) Similar phenomena has been also discovered for the ionic conductor of samarium doped ceria (SDC) and SrTiO3.(3) Pure semiconductors, on the other hand, have very recently been successfully applied in fuel cells: e.g. a layer-structured metal oxide LiCo0.5Al0.5O2 turned to a good proton conductor in fuel cell operation resulting in 150 mW/cm2 at 600 °C;(4) and a perovskite oxide, SmNiO3, with high intrinsic electronic conduction, experiencing a Mott transition as pure proton conductor resulting in 225 mW/cm2 at 500 °C.(5) The same material and proton transport property have further been investigated both theoretically and experimentally in electrochemical device applications.(6)

Combining band structures with ionic species/transport and e-i (electron-ions)/semiconductor-ionic coupled effects could be better alternative to traditional ionic electrolyte fuel cell technologies.

1. J. Garcia-Barriocanal, A. Rivera-Calzada, M. Varela, Z. Sefrioui, E. Iborra, C. Leon, S. J. Pennycook, J. Santamaria, Colossal Ionic Conductivity at Interfaces of Epitaxial ZrO2:Y2O3/SrTiO3 Heterostructures. Science 321, 676-680 (2008)10.1126/science.1156393).

2. S. Lee, W. Zhang, F. Khatkhatay, H. Wang, Q. Jia, J. L. MacManus-Driscoll, Ionic Conductivity Increased by Two Orders of Magnitude in Micrometer-Thick Vertical Yttria-Stabilized ZrO2 Nanocomposite Films. Nano Letters 15, 7362-7369 (2015); published online Epub2015/11/11 (10.1021/acs.nanolett.5b02726).

3. S. M. Yang, S. Lee, J. Jian, W. Zhang, P. Lu, Q. Jia, H. Wang, T. Won Noh, S. V. Kalinin, J. L. MacManus‐Driscoll, Strongly enhanced oxygen ion transport through samarium-doped CeO2 nanopillars in nanocomposite films. Nature Communications 6, 8588 (2015)10.1038/ncomms9588

https://www.nature.com/articles/ncomms9588#supplementary-information).

4. R. Lan, S. Tao, Novel Proton Conductors in the Layered Oxide Material LixlAl0.5Co0.5O2. Advanced Energy Materials 4, 1301683 (2014)10.1002/aenm.201301683).

5. Y. Zhou, X. Guan, H. Zhou, K. Ramadoss, S. Adam, H. Liu, S. Lee, J. Shi, M. Tsuchiya, D. D. Fong, S. Ramanathan, Strongly correlated perovskite fuel cells. Nature 534, 231 (2016)10.1038/nature17653

https://www.nature.com/articles/nature17653#supplementary-information).

6. Z. Zhang, D. Schwanz, B. Narayanan, M. Kotiuga, J. A. Dura, M. Cherukara, H. Zhou, J. W. Freeland, J. Li, R. Sutarto, F. He, C. Wu, J. Zhu, Y. Sun, K. Ramadoss, S. S. Nonnenmann, N. Yu, R. Comin, K. M. Rabe, S. K. R. S. Sankaranarayanan, S. Ramanathan, Perovskite nickelates as electric-field sensors in salt water. Nature, (2017)10.1038/nature25008

https://www.nature.com/articles/nature25008#supplementary-information).

Dear Prof Bin

I really appreciate the question and the answers added by Prof Kaisan and prof Abdelhalim. Please can you clarify how can we interlink the excited electron (which still inside the space charge of the semiconductor) with the already liberated ions (already lose its electron and become positively charged ion )?

With my best Regards,