Which is currently being taught; electron flow or conventional flow?

[unitedatoms]

Thanks to random historical agreements and npn. At this era the rail at top of diagram is positive, ground is zero and arrows on schematics are more or less readable. Or else the schematology would be unlearnable.

What is still confusing are small things, which one can stop noticing after a while. For example the symbol for battery has positive plate drawn smaller than negative. Other annoyance is arrow direction on current source symbol. This current source (I can not even remember it correctly for longer than a minute) is worst.

Edit: However not everything is safe to talk about, because if aliens with all reasonable choices of polarities and flows will meet us, the shameful state of our science may cause an enragement and intergalactic war.

[newbrain]

An NPN transistor is used in a negative ground circuit and the transistor symbol has the arrow pointing AWAY from the device
AN N-Channel MOSFET is used in a negative ground circuit and the MOSFET symbol has the arrow pointing TOWARDS the device.

First of all, negative or positive grounds have nothing whatsoever to to do with it.
I'm sure you know you can use PNP BJTs and P-channel MOSFETs in a circuit with a "negative" ground - after all, ground is just the place you pick and say "this is my 0 V reference".

N-channel MOSFETs have a p doped semiconductor for substrate, and that explains the arrow pointing in, as for a PNP BJT.
As the the p substrate will form a PN diode with the Drain (and possibly the Source  if it's a separate terminal), the arrows gives you the right indication!

EtA: I really don't get all the fuss. What's so complicated in understanding that as defined current goes from higher potential to lower potential. Since the current carriers are most of the time electrons, and they have a negative charge, they go the opposite way.
My description of how a triode works is not going to change for this.

[madires]

If the type of flow is not specified, which is the correct one to use?

If not specified or not obvious from the context we assume the conventional flow (another convention ).

[T3sl4co1l]

In a similar vein there is something that I need help with

An NPN transistor is used in a negative ground circuit and the transistor symbol has the arrow pointing AWAY from the device

AN N-Channel MOSFET is used in a negative ground circuit and the MOSFET symbol has the arrow pointing TOWARDS the device.

Please could someone explain what is going on here?

The arrow shows the direction of minority charge carriers, technically speaking.  Practically, that means there's a P-N diode junction there.

The BJT is a trans-diode, with the B-E side being the primary (controlling) diode, and C-B (no arrow, though early (dual whisker) types were often drawn that way) being controlled consequentially.

The MOSFET acts in parallel with a (body/substrate) diode.  The gate biases a surface layer into conduction, bypassing the diode; the layer carries a current regardless of polarity -- hence why synchronous rectification works.  Because there are effectively two paths in reverse, there's a junction dot in the symbol, showing one current path through the substrate diode (which is normally reverse biased in switching and amplifier service) and one through the channel (which is conditionally conductive).

Such a superficial explanation does of course miss how BJTs can saturate at low or negative voltages, which they actually do, much like FETs; but it fits naturally with Darlington and IGBT types, which do not saturate all the way to zero.

So now that you know this, whenever you see the shorthand MOSFET symbol,



your eyes may see: "wait, that's a diode shorting from top to bottom!"  Well, yeah, without mincing words: it's a retarded symbol.  What they meant was a regular NMOS I guess drawn in the style of an NPN, but what they got was something entirely different.

Ironically, this is a fine way to draw an IGBT, though with angled C/E lines; that is, as a BJT with insulated gate instead of base wire.

Also incidentally, the MOS IC shorthand omits the arrow, and denotes channel type by omitting or placing a circle on the gate (to suggest negation for the P-ch).  This is perfectly fine, and consistent with IC design (where you do in fact have independent, and usually symmetric, D and S connections, and a common substrate to VDD/VSS that can be assumed when not indicated otherwise).

Tim

[SiliconWizard]

Also incidentally, the MOS IC shorthand omits the arrow, and denotes channel type by omitting or placing a circle on the gate (to suggest negation for the P-ch).  This is perfectly fine, and consistent with IC design (where you do in fact have independent, and usually symmetric, D and S connections, and a common substrate to VDD/VSS that can be assumed when not indicated otherwise).

Yes, much better! Unfortunately, the above symbols I mentioned and you showed are still frequently used in microelectronics courses and schematics...

[SparkyFX]

Over here the nomenclature taught is "technical" and "physical" direction. As all schematic symbols use the technical direction (and make more sense applying them), it is hard to come up with an example in which it actually matters as long as all schematic symbols are drawn following the methodology. It only breaks the system when someone tries to mix both.

But anyway, i like the approach of seeing an electron as a negative charge moving in a certain direction.

[vk6zgo]

When discussing something like how current travels through a transistor do professors and/or people in the industry describe the behavior in terms of electron flow or in conventional flow? I know that the difference between electron flow and conventional flow is taught, but if the flow type is not specified how do you know which is being used?

I came across some course material that described the operation of an NPN transistor in the same way that I would expect a PNP transistor to be described - I thought that it was an error, however it was intentional. Depending upon which flow the describing person is using, either could be correct. If the type of flow is not specified, which is the correct one to use?

(Attachment Link)

Going back to this original posting, the vital clue is in the transistors pictured.
They date from an earlier period, as does the information shown with them.

In the late 1950s, to mid '60s, if you did any formal course in Semiconductors at Technician level, you learnt about such things as Valency bonds, Electron energy levels, & so on.

It seemed that the Physicists didn't know how much to "dumb" things down before passing it on to the EEs, who in turn, passed it pretty much untouched to the Techs.

Your information dates from this period.

As the Physicists used Electrons & "holes", so did the material, which usually showed current as Electron Flow.
This was hardly a problem, as there were thousands of people to whom Electron Flow was not something "new & alarming", but how current flowed through vacuum tubes, & external circuitry.

At the same time, such people happily used Conventional Current Flow for calculations appertaining to motors, generators, electromagnets, etc, due to the vast quantity of material, "Right Hand Rules", & so on, available using CCF, which hadn't yet attained the "god-like" status it enjoys today amongst many.

Any information presented in that period as part of a Semiconductor course was most likely to use EF.
A lot of the stuff was interesting, but not really used every day, as circuit applications were not usually covered very intensively.

Many years later, as part of another course, I did a unit which went seriously into circuit theory, ignoring Semiconductor Physics, & effectively treating the transistor as a "black box".
This used CCF,  which didn't worry me in the least, but was much more useful in understanding the use of such devices.
Many of the design formulas are  either the same, or similar between BJTs, FETs, & vacuum tubes.

[TimFox]

The only places where I saw "electron flow current" taught instead of "conventional current" were several military electronics textbooks, from the vacuum-tube era, that were given to me as a kid by friends of the family who were veterans.  In my physics and electronics education, it was always conventional current and signed charge carriers (electrons, ions, holes, etc.)

[GlennSprigg]

"And this sacred valley here was formed by the giant snake that wormed it's way..."
Some people might believe that, for fun, (or pity them...) when we were impressionistic children.
Just because "Conventional Flow" was all that they understood at the TIME, has ZERO reason
why this preposterous notion should be even discussed in this day & age !!!   
The only underlying 'convention' is Diagrams of old, and device symbols. It has NO place today!! 

[madires]

Just saying, there are also conductors with positive charge carriers, e.g. solid electrolytes with H+ charge carriers.