Quantum Dots Get Doped

Silver and copper atoms are used to create doped nanocrystals--tiny versions of the basic building blocks of semiconductor devices

3 min read
Quantum Dots Get Doped

5 April 2011—At just a few nanometers across, quantum dots are tiny—so tiny that scientists attempting to insert new atoms into their structures have found that the atoms tend to quickly wander back out.

Now an Israel-based team has made these atoms stick, creating the first pairs of p-type and n-type semiconductors, pint-size versions of the building blocks of today’s diodes and transistors. The work could eventually pave the way for new flexible solar cells and LEDs, which would be built from the bottom up.

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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
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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.

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