Team develops method for creating 3D photonic crystals

Nov 07, 2011
Electron micrograph of a three-dimensional diamond structure in silicon (outlined). The scale bar in the top right corner represents a distance of 2 micrometres, which is about one fiftieth the thickness of a human hair. The object on the upper left-hand side is a dust particle that settled onto the crystal after the etching procedure.

Dutch researchers at the University of Twente's MESA+ research institute, together with ASML, TNO (the Netherlands Organisation for Applied Scientific Research) and TU/e (Eindhoven University of Technology) have developed a method for etching 3D structures in silicon. These structures behave as photonic crystals (semiconductors for light), making it possible to manipulate light in all sorts of novel ways. For instance, you can use them to "trap" light, or to create zones that are impenetrable to light of specific wavelengths. This method brings the optical computer (a much faster type of computer that uses optical bits instead of electronic ones) one step closer. The researchers give details of their method in two articles that will soon be published in the scientific journals Advanced Functional Materials and the Journal of Vacuum Science and Technology B.

Moore's Law states that the number of transistors that can be mounted on a computer chip will double every two years. However, it is becoming increasingly difficult to reduce the size of transistors any further. So, given the limitations of current technology, Moore's Law will not be applicable for very much longer. One way around this problem is to stack the transistors in three dimensions (3D). Researchers at the University of Twente have developed a method for making 3D structures out of silicon. These structures behave as semiconductors for light, making it possible to manipulate light in all sorts of different ways. For instance, these structures make it possible to trap light, or to create zones that are impenetrable to light of specific wavelengths.

These structures are produced using standard equipment developed for the manufacture of . This has various practical benefits. For example, the structures are easier to produce and they can be integrated with electronic components on .

Model of a diamond structure (red balls and grey bars) superimposed on the 3D silicon structure. The similarities between the diamond lattice and the artificial structure are clearly visible here.

The method consists of two steps. In the first step, millions of are etched into the upper surface of a wafer of silicon. Just 300 nanometres in diameter and less than 8 micrometres deep, these holes are too small to see, even with the aid of an optical microscope. The second step involves the truly innovative aspect of this method, and is therefore the toughest. The wafer is tilted and millions of tiny holes are then etched into the side of the silicon, in the same way as before. In order to obtain the requisite structure, the second structure has to be aligned extremely accurately relative to the first structure. The maximum permissible deviation is just 30 nanometres and half a degree. The created in this way have tiny pores that intersect at an angle of 90 degrees. The material has a structure resembling that of a diamond crystal, but larger by a factor of 2000.

The study was carried out in the department of Complex Photonic Systems (COPS), and at the University of Twente's MESA+ research institute. This involved close collaboration with researchers from ASML, Eindhoven University of Technology, and TNO. The study's sponsors included NanoNed/STW, the FOM Institute, and the Netherlands Organization for Scientific Research (NWO).

Explore further: 'Dressed' laser aimed at clouds may be key to inducing rain, lightning

add to favorites email to friend print save as pdf

Related Stories

Fabricating 3D Photonic Crystals

Jan 21, 2009

(PhysOrg.com) -- “In photonic crystals, the ability to control the structure of a material in full three dimensional space, allows you to control the way that light flows through it,” John Rogers tells PhysOrg.com. “Thi ...

Electrons seem heavier in extremely thin silicon

Apr 01, 2011

For years now, transistors have been getting smaller and smaller. Research conducted by Jan-Laurens van der Steen of the MESA+ Institute for Nanotechnology at University of Twente, The Netherlands, has shown that electrons ...

Microtechnology: An alignment assignment

Jan 21, 2011

Microelectromechanical systems (MEMS), which consist of tiny moving parts driven by electrical signals, have found ready applications in optical communication systems. They are attractive in part because they ...

Recommended for you

Robotics goes micro-scale

Apr 17, 2014

(Phys.org) —The development of light-driven 'micro-robots' that can autonomously investigate and manipulate the nano-scale environment in a microscope comes a step closer, thanks to new research from the ...

High power laser sources at exotic wavelengths

Apr 14, 2014

High power laser sources at exotic wavelengths may be a step closer as researchers in China report a fibre optic parametric oscillator with record breaking efficiency. The research team believe this could ...

User comments : 5

Adjust slider to filter visible comments by rank

Display comments: newest first

Isaacsname
not rated yet Nov 07, 2011
That's a lot of surface area. I wonder if different designs would yield any interesting results ?

http://en.wikiped...m_tiling
Nerdyguy
not rated yet Nov 07, 2011
"...these structures make it possible to trap light, or to create zones that are impenetrable to light of specific wavelengths."

Lots of researchers chasing this idea. I wonder when we'll finally see this technology go to market?
Eikka
not rated yet Nov 07, 2011
Moore's Law states that the number of transistors that can be mounted on a computer chip will double every two years.


No it doesn't.

It's interesting that Physorg can get Moore's law wrong every single time they mention it in a report.

There is no technical limit on how many transistors can be placed on a silicon chip - you can always make the chip bigger. The only limit is price.
Nerdyguy
not rated yet Nov 07, 2011
Moore's Law states that the number of transistors that can be mounted on a computer chip will double every two years.


No it doesn't.

It's interesting that Physorg can get Moore's law wrong every single time they mention it in a report.

There is no technical limit on how many transistors can be placed on a silicon chip - you can always make the chip bigger. The only limit is price.


Umm, yes, actually, it does.

From Intel's website:
"His bold prediction, popularly known as Moore's Law, states that the number of transistors on a chip will double approximately every two years.

You're playing semantics suggesting that you can make the chip bigger. Moore's practical concern amounted to smaller = better, and that's still a fundamental concern in chip making. I could give you a boatload of links, but why bother. Ever held a cellphone?
Isaacsname
not rated yet Nov 09, 2011
Couldn't they use beam shaping to excavate different geometries ?

More news stories

Making graphene in your kitchen

Graphene has been touted as a wonder material—the world's thinnest substance, but super-strong. Now scientists say it is so easy to make you could produce some in your kitchen.