Silicon is easier to work with, but it's reaching its limit

Dec 20, 2014 07:40 GMT  ·  By

With Moore's Law less and less likely to survive on the current model of central processing units and semiconductors in general, chip designers are looking into alternatives to not just processor architectures, but the materials they consist of.

For those unaware, "Moore's Law" is the observation that, over the history of computing hardware, the number of transistors in a dense integrated circuit doubles around every two years, usually without an attached price rise.

This brings better performance and energy efficiency. Also, it provides a solid reason to get new chips, and thus, lets companies add extra technologies and features all the time.

Pretty much all semiconductors used by the world at large are made of silicon. That means CPUs, NAND Flash chips, DRAM chips, ICs, you name it.

Alas, silicon is starting to strain under the demands of Moore's Law. It's why graphene is being so heavily researched and why researchers from Purdue University have just demonstrated a second alternative to silicon: germanium.

Germanium-based chips could replace silicon even before graphene

Graphene may promise outright miraculous gains in not just semiconductors but also many other products and technologies. However, it's not the easiest to work with.

True, germanium isn't exactly easy to work with either. In fact, in a very ironic (retroactive) twist, the first transistor ever made, created by Bell Labs in 1947, was made of germanium, not silicon. However, it was soon abandoned in favor of the more malleable and easier to process silicon.

Now, silicon miniaturization is bringing more and more difficulties, so Purdue University engineer Peide Ye and colleagues started developing germanium circuits again.

Germanium's inherent properties make it suited for faster circuits than silicon but can be processed on the same manufacturing techniques used for current chips (complementary metal-oxide semiconductor, or CMOS).

This, as it happens, is something beyond graphene technology researchers at the moment and why germanium-based processors could be ready for deployment in a few years, as opposed to the one or two decades of the former.

Classification of germanium circuits

The plan is to stick to the current CMOS circuit model, consisting of nFETS (transistors that conduct negative charges) and pFETS (positive charges).

Germanium pFETS were readily enough created, but nFETS proved problematic all those decades back, hence why the element was set aside in favor of silicon. Purdue University engineer Peide Ye was finally able to make a new design for nFETS, one that offers much better performance too.

Meanwhile, electrical engineer Krishna Saraswat was the one who prompted the new interest in germanium thanks to his 2002 paper describing high-performance germanium transistors (2-3 times better than silicon equivalents).

All chips could be made of Germanium in a few years (4 Images)

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