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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

Sunday, December 30, 2018

#396 2019

To all of you who visit this site, the very best wishes for the great New Year 2019!  Be on the lookout for the new entries coming out soon!


Posted by Jerzy Ruzyllo at 03:00 PM | Semiconductors | Link

Sunday, December 9, 2018

#395 It's IEDM time

Starting over ten years ago (see blog #5 posted in 2007) I like to remind you at this time of the year about IEDM (International Electron Device Meeting) which is a flagship semiconductor conference.


You may want to check the program of 2018 IEDM here.

Posted by Jerzy Ruzyllo at 03:13 AM | Semiconductors | Link

Sunday, November 4, 2018

#394 Organic solar cells

In the new generation photovoltaics special role is played by organic solar cells, or in other words, solar cells manufactured using organic semiconductors.


Organic solar cells are squarely at the other end of the efficiency paradigm than high-end solar cells solar cells mention earlier, but due to some unique features and low cost are bound to play a role on the photovoltaics arena.


Similarly to OLEDs (organic light-emitting diodes) the mechanism of light conversions into electricity is here somewhat different than in the case of inorganic semiconductor cells discussed earlier. In spite of the efficiency in the range of just few % in the basic version (efficiency increases even up to some 15% for more structurally complex configurations) and issues with stability when exposed to sunlight and elements, low-cost of organic cells combined with flexibility and transparency of the organic solar panels allows their uses in specialized applications where mostly rigid, opaque substrates based inorganic cells cannot be used.


See brief comments regarding perovskite solar cells which are in some ways similar to organic cells coming soon.

Posted by Jerzy Ruzyllo at 02:57 AM | Semiconductors | Link

Sunday, October 21, 2018

#393 High-end solar cells

As indicated earlier, silicon serves very well "mass photovoltaics". However, in order to meaningfully increase efficiency of solar cells, multi-junction, compound semiconductors-based cells known as tandem solar cells are being employed.


The goal is to improve the use the solar spectrum by stacking up semiconductors featuring different energy gaps in multi-junction cells arranged such that energy gap width increases from the bottom to the top of the stack. This arrangement assures absorption of the fairly broad range of wavelengths included in the solar spectrum with shortest being absorbed by the top layers and longer penetrating deeper into the stack where they are absorbed by the narrower bandgap materials. The result is high-cost class solar cells, but also the cells featuring the highest efficiencies approaching 50%.

Posted by Jerzy Ruzyllo at 12:34 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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