On Sun, 29 Jun 2025 20:41:05 +0000, quadibloc wrote:
In a discussion on the subject, someone noted that GaN has a high defect density. I presume that it is not as high as that of Silicon Carbide, though, or the notion of using it to build a microprocessor would be too obviously stupid for words.
I seem to have presumed wrong.
Apparently the defect density of Silicon Carbide is 10^4 defects per
square centimetre... and that of Gallum Nitride is, at best, ten times as high. (At worst, throw in another factor of 10^5.)
In a discussion on the subject, someone noted that GaN has a high defect density. I presume that it is not as high as that of Silicon Carbide,
though, or the notion of using it to build a microprocessor would be too obviously stupid for words.
On Thu, 3 Jul 2025 02:55:01 -0000 (UTC)
John Savard <[email protected]d> wrote:
On Sun, 29 Jun 2025 20:41:05 +0000, quadibloc wrote:
In a discussion on the subject, someone noted that GaN has a high defect >>> density. I presume that it is not as high as that of Silicon Carbide,
though, or the notion of using it to build a microprocessor would be too >>> obviously stupid for words.
I seem to have presumed wrong.
Apparently the defect density of Silicon Carbide is 10^4 defects per
square centimetre... and that of Gallum Nitride is, at best, ten times as
high. (At worst, throw in another factor of 10^5.)
I know next to nothing about this, but pshurely Gallium is a lot rarer (and thus more expensive) than Silicon?
GaN is seeing increasing use in power electronics - a GaN power FET
can switch a lot faster, has lower resistance, and is physically
smaller than equivalent Si transistors. But they cost several times
as much, largely because of the economies of scale for making them.
(Power electronics is a lot more tolerant of defects than CPUs,
because the geometries are vastly bigger.)
My impression is that GanFET advantages are mostly at high voltages.
Above 100V or something like that.
On Thu, 3 Jul 2025 16:45:48 +0200
David Brown <[email protected]> wrote:
GaN is seeing increasing use in power electronics - a GaN power FET
can switch a lot faster, has lower resistance, and is physically
smaller than equivalent Si transistors. But they cost several times
as much, largely because of the economies of scale for making them.
(Power electronics is a lot more tolerant of defects than CPUs,
because the geometries are vastly bigger.)
My impression is that GanFET advantages are mostly at high voltages.
Above 100V or something like that.
At lower voltages at any given current rating best available GaNFETs
tend to have higher capacitance than best MOSFETs.
Also from 1st hand experience it appears that GanFETs needs more
babysitting than MOSFETs.
On 03/07/2025 10:03, Kerr-Mudd, John wrote:
On Thu, 3 Jul 2025 02:55:01 -0000 (UTC)
John Savard <[email protected]d> wrote:
On Sun, 29 Jun 2025 20:41:05 +0000, quadibloc wrote:
In a discussion on the subject, someone noted that GaN has a high
defect
density. I presume that it is not as high as that of Silicon Carbide,
though, or the notion of using it to build a microprocessor would be
too
obviously stupid for words.
I seem to have presumed wrong.
Apparently the defect density of Silicon Carbide is 10^4 defects per
square centimetre... and that of Gallum Nitride is, at best, ten
times as
high. (At worst, throw in another factor of 10^5.)
I know next to nothing about this, but pshurely Gallium is a lot rarer
(and
thus more expensive) than Silicon?
As an element, yes, it is much more expensive. I bought some gallium metal, because it is fun to play with - but it was not a cheap toy!
However, the cost of making devices from a particular element or
molecule is vastly more complicated than the rarity of the raw material.
You can pick up a rock from your garden and you'll have enough silicon atoms for a wafer, but only traces of gallium. The cost of a silicon wafer (even before putting anything on it) will exceed the worth of its weight in gallium by a factor of 20 or so. It's the purification and growing virtually defect-free crystals that costs money - the cost of
the raw material elements is almost negligible.
GaN is seeing increasing use in power electronics - a GaN power FET can switch a lot faster, has lower resistance, and is physically smaller
than equivalent Si transistors. But they cost several times as much, largely because of the economies of scale for making them. (Power electronics is a lot more tolerant of defects than CPUs, because the geometries are vastly bigger.)
| Sysop: | Keyop |
|---|---|
| Location: | Huddersfield, West Yorkshire, UK |
| Users: | 715 |
| Nodes: | 16 (2 / 14) |
| Uptime: | 11:08:09 |
| Calls: | 12,100 |
| Files: | 15,003 |
| Messages: | 6,517,992 |