Applause on the highlight. Applause on the bloom. Applause on the kind words. On a side note: he does sund like the Tesla weirdo.
That was a 24 years old patent for low temp radiation detector technology i picked randomly with google...You don't measure a noiseless transducer with a noisy setup...you measure the noise of the detector with a noiseless setup...
https://www.radiation-dosimetry.org/what-is-ln2-cryostat-cooling-of-hpge-detectors-definition/What's a superdiode or just a thermally coupled diode doing in a silicon stage to cancel the final transistor current drift ? What's a bandgap temp sensor doing?
Do you really need to go on like this?
@JMFahey
You think you're talking with the carpenter? You're right.I did carpentry for a full year...24 years ago.
You do not need to go anywhere, of course, you can go anywhere you like. We don't care. That's entirely your desision.
The same as it is your decision to randomply pick up Google Search.
The same as it is your decision to randomply pick up Google Search.
No, the Ube is not the only advantage, but, is good to have. Low Ube is not, only, advantageous for low voltage, but, for many other circuits. The noise is lower, the speed can be higher, again, EVERY PARAMETER IS BETTER, except their thermal endurance, which, is not a big deal. And, yes, there are high speed Ge transistors, yet, difficult to find. Obviously, you are not familiar with Ge transistors, this is why I am not interested in your and other comments. Yes, your comments are nonsense.
Nonsense is also to compare 1950's transistors with 2022 transistors. In case they made Ge transistors NOW, they would be much better than Si transistors now in every form and shape ( except thermal endurance ).
This is, also, why I am not interested in your and other, similar comments. I AM ONLY INTERESTED IN THE NUMBER ( MAKE AND MODEL ) OF HIGH FREQUENCY, possibly, complementary, Ge TRANSISTORS, which can take 40V Uce. For the 1950's, this was difficult. Even now, high speed Si transistors have low Ucemax. Hopefully, there are some around. May be, Made in The USSR.
So, in case anyone has the exact numbers, please, inform. And no, Internet is not a good source, because, there is no exact information ( other than NTE ) on Ge transistors. There is, only, general nonsense as your comments, which, try to prove the unprovable. Ge is a superior material and, again, the only reason to switch to Si was price, availability and ease of manufacturing.
Looks like AC122 is slow, but, most importantly, does not seem to have a complementary NPN. Exact complementary is not important. Somewhere there is good enough.
True. In case they made Ge transistors now, they would be unbelievably much better. Hope they would soon. They talk of Ge MOS transistors, but, not Ge bipolars.
I do not need them to drive speakers ( for power applications ). I want them in the range of 2N3904 and 2N3906, low power, signal. The Ge transistors will drive high power Si or, even, low power Si, which, in turn, would drive high power Si.
In some applications, I would be happy to use them as pure common emitter. In most application, a common collector buffer. I want the buffer to be lighting fast, though, which, I doubt these transistors can achieve.
Yes, 2N3055 and MJ2955 are very slow, however, very powerful. I need something to drive slow, high power transistors ( usually, Toshiba as they are the fastest and the best ) such as 2N3055 and MJ2955.
So, the Ge transistors can be low power, signal transistors. High Frequency Ge transistors are very welcome, but, I am not sure these can reach 40V in the 50's. Their power was very limited too.
FET's will not do. Amplifiers would not either. FET's have a very large gate source voltage and are slow with huge gate source capacitance.
And I gave you most or all parameters in the first post.
Again, the only reason they do not make Ge transistors is price, availability and manufacturing difficulty. Otherwise, they would, because they would be better. No one is interested to make better. They want inexpensive.
I have found GT402G and GT404G. Faster than these would be preferable. Their leakage current is higher, but, this may not be very important in some cases.
Forgot to mention : 1950's Ge transistors have a higher leakage current than contemporary Si transistors. This may be important in some cases. However, in case there were contemporary Ge transistors, their leakage current would be lower.
OK. I ve read through the first page of the thread. Hopefully, I would be able to do more, but, because of many comments, most of them useless, I cannot do so.
Here are the translated datasheets of GT402 and GT 404, whoever is interested :
https://drive.google.com/drive/folders/1xH0_UTeCrvTPOc40wg_NzldcV2bCAMNh
Here are the translated datasheets of GT402 and GT 404, whoever is interested :
https://drive.google.com/drive/folders/1xH0_UTeCrvTPOc40wg_NzldcV2bCAMNh
I keep some Germanium transistors around because I have a Farfisa Compact Duo organ that's full of them for the master oscillators and the flip-flop octave dividers that produce the different octaves of tones. If divider transistors fail, you usually have to replace them as pairs, matching as closely as possible for Vbe. There are 12 Ge transistors on each tone card, and there are 12 tone cards, so that's 144 of them, plus a few on the audio output boards, probably around 150 Ge transistors in total.
On the old ones, the leads sometimes spontaneously break off, and problems can arise if they develop too much leakage. For example, a master oscillator will not tune with the given range of tuning inductor adjustment. Luckily, I have an old Heathkit transistor tester that tests for leakage. Ge transistor leakage will also throw off hfe readings you might try to get from a DMM with a transistor test, so it's pointless to try to test them that way.
On the old ones, the leads sometimes spontaneously break off, and problems can arise if they develop too much leakage. For example, a master oscillator will not tune with the given range of tuning inductor adjustment. Luckily, I have an old Heathkit transistor tester that tests for leakage. Ge transistor leakage will also throw off hfe readings you might try to get from a DMM with a transistor test, so it's pointless to try to test them that way.
"However, in case there were contemporary Ge transistors, their leakage current would be lower."
THeir leakage might be lower than 1950's Ge but they will never be lower than silicon.
You need to learn about band gaps and leakage currents.
THeir leakage might be lower than 1950's Ge but they will never be lower than silicon.
You need to learn about band gaps and leakage currents.
Still, insignificant.
Many people need to learn of electron mobility. This is said to be much higher in Ge than in Si. This is why, people now say to make MOS transistors with Ge too along with other elements. They promise to be faster.
Because Si is so bad, people in the 80's hoped GaAs would be the revolution, but, this did not happen on a huge scale.
Now, GaN MOS transistors are very popular for their endurance. Clearly, Si is not the best choice. Yet, Si is the most inexpensive and easy to make trillions of pieces of. And can take temperature and, therefore, power.
Yes Si is so bad its still holding its own against GaNFETs despite the huge difference in figure of merit... Silicon is a wonder material for fabrication - its oxide forms a fantastically performant insulating film for FET gates and other insulation purposes, dangling bond problems are easily fixed with hydrogen passivation (big problem for Ge FETs). Many different dopants can be used to make it p-type or n-type over a wide range of concentration levels and it takes well to ion-implantation and subsequent rapid annealing. Its a good conductor of heat, has low thermal expansion, high heat capacity, high breakdown field-strength and leakage isn't generally an issue till 100C or so (excepting Schottky junctions that is). In fact its the substrate of choice for most exotic semiconductor devices too.
Si took over from Ge because it proved so much easier to tame - so Ge tech lacks far behind - however the big issue is thermal performance, Ge will never regain the ascendency because of that I think - you need to handle the heat and conduct it away, Si is far better than Ge for that. Hybrids of various kinds are llikely to become increasingly used - heterojunction technology, 2D electron gas, band-gap engineering, its what's pushing performance in many areas
For audio kinds of speeds (ie super slow), Si has perfectly adequate mobilities. In fact any inorganic semiconductor is good enough I suspect.
Do you actually know what carrier mobility is? Its not the same thing as speed. If you can make smaller devices, they will go faster for the same mobility. This is why CPU FETs can switch in a few dozen picoseconds despite being slow old silicon (well, perhaps strained silicon, but still)! - they are very very small, mobility is less limiting. Its also why power MOSFETs are actually arrays of small MOSFETs all in parallel with vertical current flow - minimizes the distance carriers have to travel to traverse the gate - faster operation.
Most automotive certification grades would preclude any pure Ge device as they can't handle the > 100C operating range required. The thermal weakness of Ge is a big issue - I doubt you can reflow solder Ge components with standard equipment/solder as the dopants start to diffuse about at such temperatures, degrading the device.
I read somewhere of a SiGe heterojunction atop a Si transistor getting 800GHz transition frequency (800GHz, not 800MHz). These semiconductor engineers really know what they are doing to get the best out materials. I think we'll let them figure this out.
And did you know enhancement-mode power GaNFETs are actually made with a silicon MOSFET cascoded into a depletion mode GaNFET? Doesn't slow them down noticably, they are still limited for switching speed principally by the package inductance.
If you want to learn basic semiconductor physics I highly recommend this MIT course: https://www.edx.org/course/electronic-materials-and-devices
Si took over from Ge because it proved so much easier to tame - so Ge tech lacks far behind - however the big issue is thermal performance, Ge will never regain the ascendency because of that I think - you need to handle the heat and conduct it away, Si is far better than Ge for that. Hybrids of various kinds are llikely to become increasingly used - heterojunction technology, 2D electron gas, band-gap engineering, its what's pushing performance in many areas
For audio kinds of speeds (ie super slow), Si has perfectly adequate mobilities. In fact any inorganic semiconductor is good enough I suspect.
Do you actually know what carrier mobility is? Its not the same thing as speed. If you can make smaller devices, they will go faster for the same mobility. This is why CPU FETs can switch in a few dozen picoseconds despite being slow old silicon (well, perhaps strained silicon, but still)! - they are very very small, mobility is less limiting. Its also why power MOSFETs are actually arrays of small MOSFETs all in parallel with vertical current flow - minimizes the distance carriers have to travel to traverse the gate - faster operation.
Most automotive certification grades would preclude any pure Ge device as they can't handle the > 100C operating range required. The thermal weakness of Ge is a big issue - I doubt you can reflow solder Ge components with standard equipment/solder as the dopants start to diffuse about at such temperatures, degrading the device.
I read somewhere of a SiGe heterojunction atop a Si transistor getting 800GHz transition frequency (800GHz, not 800MHz). These semiconductor engineers really know what they are doing to get the best out materials. I think we'll let them figure this out.
And did you know enhancement-mode power GaNFETs are actually made with a silicon MOSFET cascoded into a depletion mode GaNFET? Doesn't slow them down noticably, they are still limited for switching speed principally by the package inductance.
If you want to learn basic semiconductor physics I highly recommend this MIT course: https://www.edx.org/course/electronic-materials-and-devices
Still, insignificant.
Not if you are concerned about low power systems - or even modest power systems and performance at temperature. Ge just becomes the proverbial sieve at 100C, and has trouble at 50C.
Some people do indeed need to learn about mobility. The low field mobility in Ge is about 2.5 times higher than in silicon. But once you start applying high fields, the field induces additional energetic collisions which degrade it. Silicon actually has a higher saturation velocity than Ge above 10k V/cm. And in short channel MOSFETs the surface electric field is very high. And that causes degradation.
So small geometry devices aren't going to see the full 2.5x improvement, and will be lucky to see any actual advantage.
Novel devices which keep carriers away from surfaces may see a nudge improvement, but a lot of the time engineers are looking to combine Ge with Si as you say, but silicon still has a benefit of simpler manufacturing, although current stacked gates and surround gate MOSFETs are quite different from older surface FET devices, but they won't work much above a couple of volts due to direct tunnelling, or breakdown if you like to think of that. GaN does offer some improvements in breakdown fields but the technology is still young compared with silicon.
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