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When I typed N-Channel enhancement MOSFET into Google, I saw some MOSFET symbols with or without diodes.

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This picture is taken from https://en.m.wikipedia.org/wiki/File:Enh_N_channel_Mosfet.svg

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This picture is taken from https://byjus.com/physics/mosfet/

Which one of these is named an N-channel enhanced MOSFET? And then, what is the full name of the other one? What is the difference between them? Is there a difference between representing with a normal diode and representing with a zener diode?

If they are the same, can I use any of them to refer to any MOSFET? Then why does the symbol include an extra diode?

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    \$\begingroup\$ See this excellent answer to another question. It explains why (all discrete) MOSFETs have body diodes. \$\endgroup\$
    – marcelm
    Commented Apr 30 at 19:34

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The two symbols both represent the same device, an n-channel enhancement-mode MOSFET, though the one with the diode attached may have an external diode added.

A MOSFET inherently contains a diode from source to drain. There's no way to eliminate it while keeping the device functional.

The diode may be shown as a standard pn diode or as a zener diode; the use of a zener symbol is to emphasize that the body diode in most MOSFETs is capable of avalanching non-destructively, like a zener. It does not typically have its breakdown voltage well-specified like a zener does; only a minimum is usually specified.

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  • \$\begingroup\$ ... and sometimes the diode has Schottky symbol because there is an actual Schottky diode inside, shunting the body diode \$\endgroup\$
    – fraxinus
    Commented May 1 at 11:07
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On both of these symbols shown the N-channel enhanced MOSFET. The first one shows a built-in body diode. And the second one does not show this diode as a separate component, but it's there. Practically all discrete MOSFETs will have a body diode regardless of whether it is shown on the MOSFET symbol or not.

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Both symbols are for n-channel, enhancement mode MOSFETs. One has an internal zener diode called a body diode, and one does not.

https://en.wikipedia.org/wiki/Power_MOSFET#Body_diode

The body diode is a feature of a power MOSFET's construction. I didn't find an explicit reference, but, in my experience, small-signal FETs such as the 2N7000 do not have one.

https://en.wikipedia.org/wiki/MOSFET#Circuit_symbols

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    \$\begingroup\$ I'm not aware of any MOSFET structure that doesn't have a body diode. Lateral MOSFETs have them too. Are you sure? \$\endgroup\$
    – Hearth
    Commented Apr 30 at 19:11
  • \$\begingroup\$ JFETS don't usually have them, and it's hard to see how a thin layer of glass would create one if added. MOSFET geometry is usually modified from that old model, though, for better performance. Power MOSFETs in particular have geometries designed to dissipate high power, and that can most easily be done with the drain connection on the substrate to handle more current and more importantly dissipate more heat (which is why the drain often has a larger tab). Also, see ww1.microchip.com/downloads/en/DeviceDoc/20005696A.pdf, which is unique in my experience. \$\endgroup\$
    – Cristobol Polychronopolis
    Commented Apr 30 at 20:50
  • \$\begingroup\$ @CristobolPolychronopolis There are more differences between a JFET and a MOSFET than just the layer of glass; the doping profile is entirely different. While the geometry is different for a vertical FET, the overall construction is still the same; the body diode is still there. \$\endgroup\$
    – Hearth
    Commented May 1 at 0:36

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