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Sunday, July 14, 2019

#406 Photonic alternative

In another solution, electron as an information carrier is replaced by the photon, representing quantum of light. Photon is more efficient than electron information carrier as it can cover distances in the waveguides with very little losses, which is in stark contrast to electron moving in semiconductors and metals with significant losses.


With short wavelength laser diodes and detectors available, and optical waveguides technology being well develop, a still missing link in this “all photonics” scenario is a high-performance optical transistor needed to turn light “on” and “off”.

Posted by Jerzy Ruzyllo at 11:46 AM | Semiconductors | Link

Sunday, June 16, 2019

#405 MOSFET evolution - alternative solutions

As indicated in the previous blog, solutions concerned with materials and architecture modifications of the MOSFET may not be enough to meet anticipated future needs with regard to the performance of devices designed to carry out logic functions. Therefore, alternative solutions radically departing from the mainstream approaches to transistors’ performance improvements are pursued.


Logic circuits carrying out computational operations, operate based on the binary system needed to code and process information which basically comes to switching the system from one state to another. In electronic devices this function is very efficiently carried out by transistors which turn flow of electrons (current) on and off. The problem is that scattering of electrons moving through the solid accounts for the significant signal losses, and thus, electrons as the carriers of electric charge may not be able to support long-term needs of information processing systems.


One of the solutions being explored is concerned with transistors in which magnetic rather than electric field controls device operation and exploits the fact that in addition to electric charge, electron also features an angular momentum known as electron spin. The spin of the electron can be directed by the magnetic field either up or down. In the sense then, it represents an inherently binary system which spintronics attempts to use in a magnetically sensitive transistor, called a spin transistor, to perform logic functions.

Posted by Jerzy Ruzyllo at 07:17 PM | Semiconductors | Link

Sunday, May 12, 2019

#404 Evolution of the MOSFET

As an "old timer", I follow evolution of the MOSFET (Metal Oxide Semiconductor Field Effect Transistor) since it has began to be a go to transistor configuration. And it changed pretty drastically over the years.


The evolution is proceeding in three distinct areas: gate scaling, materials used, and transistor's architecture. Regarding gate scaling, situation is clear. Over the last 50 years gate length was reduced by three orders of magnitude, i.e. from 10 micrometer to 10 nanometer. And scaling below 10 nm is happening now. How low will it go below 5 nm, remains to be seen.


There are other ways to improve transistor performance. High electron mobility semiconductors used as channel materials are coming to the rescue. May be molybdenum sulfide, or graphene?


Finally, changes in the transistor architecture bring about improved transistor's performance without gate shortening. Transistor architecture goes vertical with FinFET being very likely just the first step. The problem is that all of the above may not be enough to assure long-term growth of computational electronics. That's why alternative to the electric charge based transistors are pursued...

Posted by Jerzy Ruzyllo at 10:40 AM | Semiconductors | Link

Sunday, April 14, 2019

#403 Image sensing relies entirely on semiconductors

The image sensing devices are designed to capture light representing image and to convert it into electrical signal. The image sensors are at the core of any imaging device such as digital still cameras, digital video cameras, mobile devices, medical, surveillance, scientific, and broadcast instrumentation and many others we rely on so heavily in our daily lives.


The message here is that the image sensing devices are operating based on the physical properties of semiconductors and are manufactured using semiconductor materials. As a result, imaging devices constitute an important segment of commercial semiconductor technology. Two the most important types of semiconductor imaging devices are both based on the physical properties of the MOS (Metal-Oxide-Semiconductor) structure. First, involves CCD (Charge Coupled Devices) image sensors. Second, CMOS (Complementary MOS) image sensors. Quite interestingly this is fundamentally the same MOS structure upon which logic cells constituting all important digital integrated circuits are constructed. Equally interesting is the fact that the silicon is a semiconductor material used to fabricate both types of devices.

Posted by Jerzy Ruzyllo at 10:36 AM | Semiconductors | Link

Sunday, March 31, 2019

#402 Microtechnology, nanotechnology... quantum technology

Some of us are not only experiencing current era of nanotechnology (1 nm = 10-9 m) from its onset, but also remember times when microtechnology (1 µm = 10-6 m) was a buzz-term in science and engineering.


If the size related trends in technology evolution were to continue, then picotechnology (1 picometer or pm = 10-12 m) should be their continuation. Let's keep in mind, however,  that the average atom is sized at some 20000 picometers. Thus, the very concept of matter manipulation at the picometer level is beyond the realm of the current understanding of how the world around us works. So, picotechnology understood as a size-based continuation of nanotechnology is not going to happen, at least not in the foreseeable future.


Instead, we are in the process of parting ways with geometrical associations and start using nature of atomic-level physical phenomena related to quantum confinement as a reference. When the size of the piece of the solid is reduced to some 10 nm or below, laws of classical physics (with which we are so comfortable!) are no longer adequately describing properties of this solid and quantum physics (which is escaping our  imagination and intuition) is taking over. At this point the term nanotechnology is no longer adequately describing technological status quo and the term quantum technology is becoming a buzz-term in science and engineering.

Posted by Jerzy Ruzyllo at 05:05 PM | Semiconductors | Link

Sunday, March 17, 2019

#401 Carry it on you, wear it...

Mentioning of sensors (previous blog) brings to mind portability and wearability of the current, and even more so, future generations of electronic and photonic devices. All that is needed is a device (sensor for instance) performing any given function (e.g. counting your steps), battery powering it up, and the means of wireless communication connecting it to the other electronic systems such as your smartphone.


In the light of the developments stressing portability, mobility, and on-the-go accessibility, permanent or temporary integration of ultra-light and ultra-low power, high-end semiconductor-based electronic and photonic devices and systems with clothes we are wearing and with our bodies (including implantation) is an aggressively pursued avenue of growth for semiconductor technology. 


And we are getting there (see examples). Consider smartwatch for instance which for all practical purposes is nothing less than the pretty advanced wearable computer in the form of a wristwatch.


Posted by Jerzy Ruzyllo at 05:54 PM | Semiconductors | Link

Sunday, February 24, 2019

#400 Semiconductors can sense

The action of “sensing”, underlying operation of a sensor,  is understood as an ability of the physical object to detect in real time changes in its physical/chemical environment and to translate these changes into a measurable signal such as an electric current.


Semiconductor materials and devices are uniquely suitable for sensing applications because, unlike metals and common insulators, several physical characteristics of semiconductors change in response to the changes of the physical or chemical characteristics of the ambient. As a result, semiconductor sensors, in various shapes and forms are at the core  sensor technology.


It goeas without saying that without various types of sensors we wouldn't be evem close to where we are in terms of technical advancements. More later...

Posted by Jerzy Ruzyllo at 04:54 PM | Semiconductors | Link

Sunday, February 10, 2019

#399 Graphene solar cells?

Recently, I came across a discussion regarding graphene solar cells. The term “graphene solar cell” implies the use of graphene as a material of which solar cell is constructed the same way inorganic (most notably silicon), organic semiconductors, or perovskite crystals are used (see earlier blogs). When used in this context, the term “graphene solar cells" seems to be somewhat misleading.


That is not to say there is no room for graphene in solar cells engineering. On the contrary, because of its distinct electrical, optical, and mechanical properties graphene is bound to play an important role in various solar cells, but rather as a part of the cell enabling its superior performance than the core material based on which cells are constructed. Whether in combination with other 2D materials (molybdenum disulfide MoS2 for instance), or with incorporation of graphene into the perovskite crystals, or with the use of graphene as a transparent, flexible contact material, there is no doubt graphene will serve various performance enhancing functions in solar cell technology. But should such cells be referred to as “graphene solar cells”? The term "graphene-based solar cells" seems to be better representing the concept of graphene use in solar cell engineering.

Posted by Jerzy Ruzyllo at 06:01 PM | Semiconductors | Link

Sunday, January 27, 2019

#398 Perovskite soiar cells

Since I’ve got into a brief overview of solar cells (see below), I cannot let it go without at least mentioning perovskite solar cells. Along with organic solar cells they represent emerging thin-film solar cell technology.


Perovskites are crystalline materials  chemical composition of which may vary significantly, but which feature the same crystal structure as calcium titanium oxide CaTiO3 (perovskite structure). They have very good solar light absorption characteristics (it means they use large portion of the solar light spectrum) and matured into cells featuring above 20% efficiency. Overall. perovskite solar cells  have a very good potential for low-cost large-scale commercialization.


In the case you are not all that familiar with perovskites check this site out. 

Posted by Jerzy Ruzyllo at 05:41 PM | Semiconductors | Link

Sunday, January 20, 2019

#397 SCST 16

Since 1989 I am involved in the organization of the International Symposium on Semiconductor Cleaning Science and Technology, SCST, under the auspicies of the Electrochemical Society. This time, symposium will be held during the ECS meeting in Atlanta, GA, Oct. 13-17, 2019.


Go to this site and check symposium G01 if interested in this topic. Or may be considering submitting an abstract? Abstarct submission site is now open

Posted by Jerzy Ruzyllo at 03:52 PM | Semiconductors | Link

‹‹ ›› is the personal blog of Jerzy Ruzyllo. With over 35 years of experience in academic research and teaching in the area of semiconductor engineering (currently holding position of a Distinguished Professor of Electrical Engineering and Professor of Materials Science and Engineering at Penn State University), he has a unique perspective on the developments in this progress driving technical domain and enjoys blogging about it.

With over 2000 terms defined and explained, Semiconductor Glossary is the most complete reference in the field of semiconductors on the market today.

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