Nanometer sized objects must have one length which is comprised between 1 and 999 nm. So definitely, you can call it a nanofilm. Of course, only new properties associated with size reduction are relevant. So the prefix "nano" should be associated with objects showing these new properties, a jump in one physical behaviour. If there is no jump (i.e. the property is still dependant of the concerning length with the same law) by changing this length from 1000nm to 1nm, "nano" should be replace by ultra-thin.

I call them ultrathin films ... as long as they maintain integrity on the surface, and are large enough to study.

Definitely we can call it a nano film or nano layer.

Nanometer sized objects must have one length which is comprised between 1 and 999 nm. So definitely, you can call it a nanofilm. Of course, only new properties associated with size reduction are relevant. So the prefix "nano" should be associated with objects showing these new properties, a jump in one physical behaviour. If there is no jump (i.e. the property is still dependant of the concerning length with the same law) by changing this length from 1000nm to 1nm, "nano" should be replace by ultra-thin.

Definitely yes

Yes.

It depends on the way your are going to use this layer. If you treat this layer along its thickness ( normal to the layer) you are facing with a nano-material and should expect effects arising form the low dimensionality and quantum confinements. otherwise, this layer could not be considered as a nanostructure.

Yes, definitely.

Absolutely, it is a nanostructured ultra thin film.

Mr. Mohammed

Thank you for your answer and all the researchers , it's seems right but don't you think the change in density of state in ultra thin layer make change in properties in spite we take the result normally or not .

Nanostructures or nanomaterials must have one dimension less then 100 nm. If your film is continues then you may call it as ultra thin film not as nano thin film. If it is discontinue thin film then you may call it and 2D nano-structure unless it has uniform morphology throughout the film.

Yes, you can call it nano thin film because the size less than 100nm.

In this case has not simple answer. If thin film has not the features in the structures (grain, defects and other) the thickness is main parameter of physical properties. If in the film have some group of the defects their size is main parameters determine of physical properties of films.

If the crystallites present in the thin film have dimensions less than 50 nm I would call them nano films. However the thickness should not exceed 50 to 100 nm either.

If any dimension lies in the range 1-100 nm it is called a nanostructure. So these films are nanostructured thin films

I thinks so

Any object that has a dimension between 1-100 nm can be thought of as a nanomaterial. As you will well know, nanomaterials have properties that can differ remarkably from those of their bulk counterparts. While compositionally they may not differ from their bulk counterparts, the fact that they show different chemical and physical properties means they would need to be treated as separate.

Nanostructured films contain one main feature：crystalline dimension between 1-100nm； maybe sometime，the thickness is less than 100nm or above ，so the crystalline dimension isthe key！

A more generalized description of nanotechnology was subsequently established by the National Nanotechnology Initiative, which defines nanotechnology as the manipulation of matter with at least one dimension sized from 1 to 100 nanometers. (see wilkipedia). So a thin film with thickness less than 100 nm is nano. But not necessary a new material. It is new if you have quantum effects or surface effects inducing new properties!

Macro, meso, micro...nano, is it so important ? One nano generally means ten minus nine meter that is ten Angstroms compare to the resolution of a hight resolution TEM that is now around one Angstrom and even less. A thin film of oxide ten Angstrom thick exhibits the tunnel quantum effect. It is not at all the case with a thickness of 100 nm. To day it seems that it is better to use nano-something in the title of a paper. I don't think that it is so important to strictly determine what is the border of what is nano or not. It is much more interesting to focus on the difference of physical properties between a bulk (big) sample and the same material at a (very) small scale.

Regards to every body.

Dear Dr. R. J. ,

Thank you very much for your answer it the better answer I read , thanks

Yes, it is a material included in nanomatrials category.

I Also agree with Mr. Amin; saying that one of the dimensions (e.g. height , width, length, diameter, radius, e.t.c.) should be less than 100nm.

A particle size close to 100nm is a tenth of a micrometer. I would prefer to call particle size less than 100nm as nano particles.

Hi folks, thanks for interesting discussion. I think that people confusing nano-materials with nano-effects in terms of solid state physics. They are not the same. For example, In terms of solid state physics if the charges are confined in all directions theses are 0D material, mobile only in one direction 1D materials etc. This usually, but not always, could be achieved in nano-scale, but in macro-scale materials these effects are not rare. Quantum well structure is one of good examples.

As for nano-materials per say, we define this term usually according to their size, so if at least one dimension is nano-scale, material, film etc could be considered in nano-scale; if material have a micro-size thickness, that it is micro-size etc, regardless of their electronic structure.

Regarding DOS: please note that many nano-scale materials, as molecules for example, they do not have even the density of state, as their electronic orbitals, they do not degenerate, you know... The other useful example is hybrid single molecular device, in which single molecule bridged by two bulk 3D electrodes. Here you have the whole collection of discussed questions: size, properties, mixture of molecular orbitals with DOS in electrodes, interfaces, etc. Indeed the same device operate in one temperature range as single molecular device, in which tunneling properties are defied by molecular barrier, but at higher temperature this effect is washed out by interface between electrode and molecule, and device behave as simple barrier device, in which the nano-scale properties could not be recorded.

Is ultra thin film in nano range a nanostructure.? It depends on the way it is grown. If it is through vapour deposition, i have my doubts. Nanostructures get produced using both up and down procedures while thin films are grown on a substrate, material different from that of the substrate.The discussion appears to mix up the two topics.Usually films are not crystalline in nature while nano-materials maintain a basic structure as size changes!

Dear Vladimir ,

Thank you very much for your useful explain ,

Regards

Dear Narendra,

Thank you Prof. Happy to discuss this with you my thin film is growth by D.C. Sputtering deposition.that I get a nano structure at the top surface.

Thanks again

Regards

The nano hype and interest are due to he newly observed properties of the nano-structures that are different from their properties in the bulk form. This is a direct result of the quantum confinement of the charge carrier that would come into play when the relevant dimension is close to , or less than the mean free path of the charge carrier. So, depending on your measurements along the thickness (perpendicular to the film) as Taghinejad mentioned The nano behavior comes into play for metal films of your dimensions, (e.g. propagation of polarized light in a Kretschmann ATR configuration, leading to enhanced EM fields at the metal/air interface, which are now in the area of plasmonics). Also, the example given by Burtman could also be understood in terms of the above definitions, i.e. in terms of ratio of the dimension to the mean free path.

Manal, your comment now satisfy me re. the top surface of sputtered deposition having a nano-structured nature..

Manal, not a problem, we are here to help. I find Dr Talaat explanation as very useful too (impurities, defects and doping are the other examples of nano-features in macro-crystal), along with many other response. By the way: superconductivity that occur in bulk materials, have a nano-scale nature, when the electrons forms pairs.... Surprisingly there are no introductory textbook on this topic.

I agree with the explanation given by Yann Girard. When size of a material es reduced, there should be change in the properties associated with size reduction, then only there is some logic to change the scale of i.e. micro to nano. Thus in my opinion when the size is less than 1 micro and the material show the properties associated with size reduction, we can call it as nano particle.

Based on my understanding, the conventional definition of nanotechnology refers to the manipulation of matter with at least one dimension sized between 1 to 100 nm. This is a size range where quantum mechanical effect plays an important role in defining the overall matter's properties. So, I think as long as a dimension of your structure is in that size-range, it can be considered as a nano structured material.

If new electron confinement effects are observed in the films, which can be related to their thickness, they can qualify as "nano structured". Thus, we have shown that during growth of uniform metal films epitaxially on Si ( i.e. Cu, Au, Ag, Al), we can follow the growth of quantum well states, in perpendicular angle resolved photoemission, and show that their energy versus thickness relationships follow simple dispersion rules. In these cases therefore, the electrons are quantized perpendicularly to the surface.

Nano is a buzz world of contemporary science. It is used for political, financial and administrative reasons. Less often there is scientific justification to use it. The world (or the prefix) is used so widely today, that it does not classifies anything anymore. If the film is 10 nm thick, it is just a thin film. If some effect appear when dimensions go below 100 nm, this is a dimmensional effects. If somebody uses nano world in the title of the project just to get financed, it is good politics but lousy science.

Only if they show emergent properties derived from quantum effects, not visible in the meso scale... not only photonic or spintronic effects, but also photochemical, biomolecular interactions... range of applications is huge, but there must be a very visible quantum effect and a clear jump in properties compared with bigger structures.

All this has been said, of course, but this is just to make a strong statement against the idea that anything in the nanoscale is nanotechnology. Ever since Feynman talk, it was very clear where the limit was. Then, politicians manage the funds, but scientists make the science!!

Unfortunatelly I have to agree with Dr. Patela about the missuse of the prefix, outside scientific circles.

http://www.zyvex.com/nanotech/feynman.html

“Nanotechnology is the application of science that deals with structures of 100 nanometers in size or smaller in at least one dimension, and involves developing materials or devices within that size.” (from Encyclopedia Britannica. Inc)

See also an Introduction:

http://hermes.esys.tsukuba.ac.jp/~other/bolotov/sinj-1.html

Dear Leonid, "Encyclopedia Britanica" (or rather some people behind its content) seems to be wrong here and some revision is needed. Classification of phenomena base only on dimensions, often lead to problems or misunderstandings. A good example may be the attempt to determine what is a thin film. We get very different answers depending on the specific field of science or experience.

Dear Leonid and Sergiusz, I would agree with Sergiusz that term nano is misused very often. you see the physics became quantum mechanics when the charges are confined at least at one direction (even in the bulk materials), which is per say nano-effect. pay attention gentlemens: you do not have to have nano-scale material to observe nano-effect! However if material scientist, who do not have a clue about quantum mechanics, will evaporate a film of sub-micron size, he will say that this film have a nanometer scale (and show the exact number, say 100 nm), and this would be 100% kosher from material science point of view. And here I will rather agree with Leonid.

I guess the discussion has been going rather too long. One finds deviation from the main question. Thanks.

Ultra thin films are interesting from many points of view, like material properties and dependence on thickness. The concept of density changes its meaning and many possible applications like quantum devices and special filters. I think the discussion is not complete. We were in the business of measurement of film thicknesses and claimed we can go down to few Angstrome level using EDXRF technique and combining it with Ion beam analysis of different kinds like RBS and ERDA techniques.