Silicon-germanium (SiGe) technology?

[Plectrum]

Found this article, a glimpse of things to come?

http://www.unaxis.com/en/at_una_823.asp

Grant.

[R.G.]

Silicon Germnanium semiconductors is a technology I first heard about from IBM's research labs. I heard about it in about 1995, when it was still secret.

SiGe is a way to insert about 2-4% germanium atoms into monocrystalline silicon. Since germanium is almost but not quite the same lattice size and structure as silicon, the atoms fit into the structure but stress the crystal bonds in a way that increases charge carrier mobility. That means that charge carriers move through the silicon crystal lattice faster.

The primary use of SiGe is to make devices that are more efficient (i.e., less power lost as heat) at frequencies from 1GHz up. They can double battery life in a cell phone, for instance, when used for the final RF power amplifier.

I don't expect SiGe to be used for individual transistors other than special high frequency ones, or that it would make a lot of difference to the audio performance of a transistor; to a GHz transistor, AM radio band and lower is effectively DC.

[mac]

Sir H C answer this to my post "SiGe Transistors" --> how would they sound like in a pedal?

"I haven't used them in pedals but I have designed ICs using them.  In general, the Vbe is very high (about a volt for most), and they have pretty low collector breakdown voltages.  Since they are so friggin' fast I would imagine that they might be hard to keep stable."

mac