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Sunday, December 13, 2020

#454 My graphene story 2008-2020

Recently, while reviewing for unrelated reason my blogs posted over the years, I realized I may have my very own graphene story to tell. Here it is, based on the blogs selected from the range of my comments on this hot topic starting twelve years ago.

 

The very first time I commented on graphene, it was in three blogs posted in April 2008. Just like everybody else I was raving about this single-atom thick carbon’s potential in semiconductor electronics. I was even more enthusiastic in December 2009 following the 2009 IEDM paper exploring graphene’s potential in very high frequency, RF circuitry applications.

 

Then, two years later I came up with a series of blogs (Jan.-Aug. 2011) which seem to indicate that I was becoming a bit more cautious about ability of graphene to serve as a panacea for the problems nagging semiconductor electronics and photonics. For instance, I was commenting on graphene’s lack of energy gap as being a potential problem and peel-off technique freeing graphene form graphite as not being a solution compatible with mainstream semiconductor device technology. In my last graphene blog in 2011 (August), I was a bit more direct with my skepticism stating that the potential of graphene in digital electronics is questionable because in the transistor structure graphene, as a semi-metal, just won’t let itself to be turned “off” completely.

 

As it turns out, I did not comment on graphene directly until June 2015 which in retrospect makes me think that nothing outstanding has been happening in graphene R&D during this time period (just to make sure, this is coming from the perspective of a neutral observer never directly involved in graphene-related research). In the meantime, however, I did take a note of the 2D competitors of graphene. First came the comment on molybdenum disulfide, MoS2, (Dec. 2012) which, in contrast to graphene features energy gap and is showing good promise in transistor applications. Then, in February 2013, I alluded to 2D silicon known as silicene which was behind, at least at that time, in terms of development, but by the virtue of being a silicon was, and continue to be my favorite (I am a “silicon guy”, by the way, and I may not be totally objective). Also, a form of carbon in between graphene and diamond, known as diamane caught my attention in February 2014.

 

Coming back to graphene, it was in June 2015 when I took note of the fact that some key electronic properties of graphene such as impressively high electron mobility, apply to the free-standing graphene only. When in physical contact with other material(s), which has to be the case when graphene is formed or deposited on solid surfaces to form functional devices, those outstanding electronic properties seem to downgrade significantly. I know, they are ways to work around this issue, but they complicated processing of graphene-based devices in a major way.

 

In February 2019 I posted my most recent graphene related blog in which I objected to the use of the term “graphene solar cells”. Why? Because in so-called graphene solar cells, graphene is playing a supporting role of the transparent contact for instance, but is not a material in which photovoltaic effect is initiated by the sunlight.

 

Don’t get me wrong, graphene, whether as a 2D sheet or in the form of 1D nanotube known as carbon nanotube (CNT) is a marvelous material and it will be, and already is, used in numerous applications including batteries, biomedicine, ITO replacing transparent contacts, packaging, sensors, supercapacitors to name just a few. Twelve years ago, I was really enthusiastic about expected graphene’s ground breaking impact in semiconductor electronics and photonics. Well, things did not turn out this way, at least not until now, but I have a strong feeling they will, in one shape or another.

 

And this is the end of my 2008-2020 graphene story.

 

Posted by Jerzy Ruzyllo at 10:25 AM | Semiconductors | Link



Semi1source.com/blog is a personal blog of Jerzy Ruzyllo. He is Distinguished Professor Emeritus in the Department of Electrical Engineering at Penn State University. With over forty years' experience in academic research and teaching in semiconductor engineering he has a unique perspective on the developments in this technical domain and enjoys blogging about it.




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