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Why are Devices...

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Pommie

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Was the OC71 Germanium? Or do we have to go back to red spot transistors.

Mike.
 

Pommie

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Hey,

I was right, OC71 was Germanium. Sad thing is, I remember using them.

Mike.
 

ericgibbs

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Hey,

I was right, OC71 was Germanium. Sad thing is, I remember using them.

Mike.

I can get even sadder than you Mike, I still have most of the ones shown on that link in stock!!!.:rolleyes:
 

crutschow

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Reasons for using silicon rather than germanium for transistors:

1) Cheaper material

2) Higher operating temperature/lower leakage at a given temperature. Silicon typically has a maximum allowed junction temperature of 125C whereas germanium is limited to about 85C.

3) Readily forms a hard oxide layer which passivates the chip surface and protects the transistors underneath. This oxide also provides the insulating layer for MOSFET gates. Germanium does not form such a hard, insulating oxide.

3) Germanium Valley doesn't sound right.
 

crutschow

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Of course the melting point of germanium is far above the point where it no longer works as a transistor.
 

audioguru

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Most germanium transistors had a very poor high frequency response.
Can you imagine a micro-processor made with millions of germanium transistors?
 

crutschow

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How do you mean "melted". The germanium is in a can where you can't see it.

But they can be more easily damaged than a silicon transistor with too much soldering heat.
 
Silicon has replaced germanium since the 1960's. Si is used for all semiconductors I work with, diodes, bjt, FET, photodiode, except for the LED. An LED is made from a compund semiconductor known as a "III-V compound". The "III-V" refers to groups III & V on the periodic chart of elements. Such compounds include GaAs, GaN, GaP, etc. The emission is much higher than group IV elements like Si, Ge, SiC, etc.

Silicon is abundant, has high temperature capability, forms great oxides which insulate and stabilize the semiconductor material, and gives good performance for semiconductor devices except LEDs.

Germanium has recently been combined with silicon to produce a bjt device. The Si-Ge combo offers high beta with low rbb' (base spreading resistance). It is useful in the base region of the bjt.

Off the top of my head, that is what I can recall. I'm too young to have worked with Ge devices, but several of my bosses who mentored me did work with Ge. Ge had high leakage current, which got worse at higher temp. Their upper temp limit is less than Si. But a Ge p-n junction has a low forward voltage drop. A Ge diode/bjt drops around 0.20-0.35V across a p-n junction, vs. 0.60-0.70V for Si.

Does this help?
 
It's too expensive, silicon performs better at a tiny fraction of the cost - the temperature of silicon is FAR higher as well.

Why not search on google for such simple questions?.

u cant trust it always, below is the reason....moreover sometimes questions arises in b/w....while reading...so i felt this as a suitable place!:)
n it helps those who would'nt thought of these type of questions!!!;):)

According to wikipedia, the melting point of Germanium is 938C. Surely not. Clicky.

Mike.

ur right... confused:confused:>>>i guess its for the impure form of Germanium?:confused:
 
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