editor's blog
Subscribe Now

Germanium-Tin Channel

Imec recently issued a press release that, early on, mentioned a “junctionless transistor.” Now… as far as I can remember back, transistors always had junctions. So I completely locked up on the question of what a junctionless transistor even means.

I got a chance to ask them when visiting their site last week. Not only is it simple, but it’s beside the point of the release. What they’re calling a junctionless transistor might simply have been called a JFET back when I was in school. Just made differently. They laid down a layer of GeSn – a very thin one over “semi-insulating silicon” (not to be confused with semiconducting silicon, of course). They then laid a fin across it. This created a depletion-mode, or normally-on, FET, with the fin controlling whether the channel conducted or not.

Pretty straightforward, conceptually. But the point of the whole thing is how they created that GeSn channel. Incorporating tin in germanium is apparently not so easy. Solubility is low, and if temperatures get too high during the process, the tin can migrate around and agglomerate in chunks instead of remaining dispersed uniformly throughout.

They came up with a relatively low-temp solid-phase epitaxy process that achieved this. Solid-phase epitaxy is a process that involves laying down an amorphous version of the desired material, followed by an anneal that crystallizes the layer.

What’s useful about this is that mobility is increased by the tin, but the tin also affects the bandgap, adding more direct bandgap characteristic, which helps with LEDs and other photonic applications. The idea is that such devices could be built on the same chip as regular silicon transistors, or heck, you could probably build them all out of this, relying on the lasing capabilities where needed. This would provide better integration of the transition between photonic and computing domains.

You can find out more in their release.

Leave a Reply

featured blogs
Dec 19, 2024
Explore Concurrent Multiprotocol and examine the distinctions between CMP single channel, CMP with concurrent listening, and CMP with BLE Dynamic Multiprotocol....
Jan 10, 2025
Most of us think we know something about quantum computing, right until someone else asks us to explain it to them'¦...

featured chalk talk

High Power Charging Inlets
All major truck and bus OEMs will be launching electric vehicle platforms within the next few years and in order to keep pace with on-highway and off-highway EV innovation, our charging inlets must also provide the voltage, current and charging requirements needed for these vehicles. In this episode of Chalk Talk, Amelia Dalton and Drew Reetz from TE Connectivity investigate charging inlet design considerations for the next generation of industrial and commercial transportation, the differences between AC only charging and fast charge and high power charging inlets, and the benefits that TE Connectivity’s ICT high power charging inlets bring to these kinds of designs.
Aug 30, 2024
36,124 views