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I remember hearing about research into germanium as a replacement to silicon or compound III-V semiconductors [1] Nanoscale devices seem like an interesting de

I remember hearing about research into germanium as a replacement to silicon or compound III-V semiconductors [1] Nanoscale devices seem like an interesting development, but all of these technologies seem like they're a decade or more away from mainstream use. [1] http://www.sandia.gov/%7Ejytsao/WCS.pdf http://www.sandia.gov/%7Ejytsao/WCS.pdf

holy_city 7y ago
I think you may mean gallium based compounds, not germanium. Germanium semiconductors are only good for sounding like Hendrix. The RF biz debated sticking with Si or moving to "wide bandgap" materials like Gallium Arsenide (GaAs) or Gallium Nitride (GaN), because the wider bandgap means the devices have much higher breakdown voltages and better power density. That means you can run them at a higher baseband and lower power without a die shrink. It's my understanding they're important for 5G devices, and they've been in the wild for awhile. But the kinds of circuit they implement are like demodulators and filters, not so much something with the transistor density of a microprocessor. I think the fab processes are well more than a decade away from reaching the die sizes of contemporary Si, even if hypothetically they could run at ridiculous clock rates and low TDP.
- benj111 7y ago
  "Germanium semiconductors are only good for sounding like Hendrix" You say that like its a bad thing.
- Junk_Collector 7y ago
  SiGe is a serious competitor to GaAs and InP. It doesn't typically have the power density of Ga derived microcircuits, but has good channel noise performance plus linearity and can operate at higher frequencies than GaAs as long as you don't need high power density. GaN has amazing power characteristics but has all kinds of issues with signal purity that are still being worked out. Eventually, I believe GaN will eat everything's RF lunch just out of sheer power efficiency gains with the last hold out being cell tower base stations, where spectral purity trumps efficiency by a mile. InP gets used into the 100GHz+ territory. These processes are mostly larger like you say, but they are also used in high end data converters (ADCs and DACs) and some processes are in the mid to low 10's of nanometers now. Which is almost exactly where silicon was a decade ago. Silicon of course isn't used because of it's performance, but rather, because silicon is the easiest of the semi-conductors to manufacture and get good yields out of. It is also comparatively very low cost. These factors have led to the lion's share of research dollars being spent there as well.
deepnotderp 7y ago
Direct S/D tunneling becomes a problem with high carrier mobility semiconductors like III-V group materials and germanium.

holy_city 7y ago

I think you may mean gallium based compounds, not germanium. Germanium semiconductors are only good for sounding like Hendrix. The RF biz debated sticking with Si or moving to "wide bandgap" materials like Gallium Arsenide (GaAs) or Gallium Nitride (GaN), because the wider bandgap means the devices have much higher breakdown voltages and better power density. That means you can run them at a higher baseband and lower power without a die shrink. It's my understanding they're important for 5G devices, and they've been in the wild for awhile. But the kinds of circuit they implement are like demodulators and filters, not so much something with the transistor density of a microprocessor. I think the fab processes are well more than a decade away from reaching the die sizes of contemporary Si, even if hypothetically they could run at ridiculous clock rates and low TDP.

benj111 7y ago
"Germanium semiconductors are only good for sounding like Hendrix" You say that like its a bad thing.
Junk_Collector 7y ago
SiGe is a serious competitor to GaAs and InP. It doesn't typically have the power density of Ga derived microcircuits, but has good channel noise performance plus linearity and can operate at higher frequencies than GaAs as long as you don't need high power density. GaN has amazing power characteristics but has all kinds of issues with signal purity that are still being worked out. Eventually, I believe GaN will eat everything's RF lunch just out of sheer power efficiency gains with the last hold out being cell tower base stations, where spectral purity trumps efficiency by a mile. InP gets used into the 100GHz+ territory. These processes are mostly larger like you say, but they are also used in high end data converters (ADCs and DACs) and some processes are in the mid to low 10's of nanometers now. Which is almost exactly where silicon was a decade ago. Silicon of course isn't used because of it's performance, but rather, because silicon is the easiest of the semi-conductors to manufacture and get good yields out of. It is also comparatively very low cost. These factors have led to the lion's share of research dollars being spent there as well.

deepnotderp 7y ago

Direct S/D tunneling becomes a problem with high carrier mobility semiconductors like III-V group materials and germanium.