The July 2022 issue of IEEE Spectrum is here!

Close bar

Thin-Film Trick Makes Gallium Arsenide Devices Cheap

Rubber-stamping makes creating solar cells, transistors, and infrared detectors easy

3 min read

19 May 2010—Researchers led by John Rogers at the University of Illinois at Urbana-Champaign have invented a cheaper way to build devices—including solar cells and infrared cameras—using highly efficient but notoriously pricey compound semiconductors. Their method, reported in the journal Nature, involves growing stacks of thin films of semiconductor, peeling off the films one by one, and printing them onto cheaper substrates, such as silicon or glass.

Silicon is the stuff of computer chips, but if you want to build the fastest transistor or the most efficient LED, compound semiconductors—such as gallium arsenide (GaAs) or gallium nitride—are your best bet. In solar cells, for instance, ”gallium arsenide is more efficient than anything known to man,” says Rogers, a materials engineer. Some GaAs solar cells can convert about 40 percent of the sun’s energy into electricity, while silicon cells max out at about 20 percent efficiency.

Keep Reading ↓Show less

This article is for IEEE members only. Join IEEE to access our full archive.

Join the world’s largest professional organization devoted to engineering and applied sciences and get access to all of Spectrum’s articles, podcasts, and special reports. Learn more →

If you're already an IEEE member, please sign in to continue reading.

Membership includes:

  • Get unlimited access to IEEE Spectrum content
  • Follow your favorite topics to create a personalized feed of IEEE Spectrum content
  • Save Spectrum articles to read later
  • Network with other technology professionals
  • Establish a professional profile
  • Create a group to share and collaborate on projects
  • Discover IEEE events and activities
  • Join and participate in discussions

3 Ways 3D Chip Tech Is Upending Computing

AMD, Graphcore, and Intel show why the industry’s leading edge is going vertical

8 min read
Vertical
A stack of 3 images.  One of a chip, another is a group of chips and a single grey chip.
Intel; Graphcore; AMD
DarkBlue1

A crop of high-performance processors is showing that the new direction for continuing Moore’s Law is all about up. Each generation of processor needs to perform better than the last, and, at its most basic, that means integrating more logic onto the silicon. But there are two problems: One is that our ability to shrink transistors and the logic and memory blocks they make up is slowing down. The other is that chips have reached their size limits. Photolithography tools can pattern only an area of about 850 square millimeters, which is about the size of a top-of-the-line Nvidia GPU.

For a few years now, developers of systems-on-chips have begun to break up their ever-larger designs into smaller chiplets and link them together inside the same package to effectively increase the silicon area, among other advantages. In CPUs, these links have mostly been so-called 2.5D, where the chiplets are set beside each other and connected using short, dense interconnects. Momentum for this type of integration will likely only grow now that most of the major manufacturers have agreed on a 2.5D chiplet-to-chiplet communications standard.

Keep Reading ↓Show less
{"imageShortcodeIds":[]}