semiconductors and so on (1 Viewer)

[wasssup]

hey guys i received an assessment on semiconductors, conductors and insulators and i was hopin could anyone out there give me some ideas to model these objects in relation to the band theory.

thanks guys

 

[Forbidden.]

I've done this one before, wrote it like any other syllabus dot point summary the el cheapo way, this should give you an idea:

Conductors have either a very small forbidden gap or no forbidden gap (because the conduction and valence band overlap each other or just touch each other)

Semiconductors have a large forbidden energy gap when they are undoped but when doped (with a Group III or V element) their forbidden energy gap is much smaller because when an electric field/current is applied electrons/electricity can flow much more easily as opposed to the undoped form.

Insulators have a very large forbidden energy gap meaning there must be a huge potential difference in order for the electrons to move from the valence band to the conduction band while overcoming the forbidden gap.

 

[wasssup]

thanks but still that does not help with my model... can any1 else help me out plz

 

[zingerburger]

Our teacher used a very simplistic model where she used an egg carton to model the valence and conduction bands, and ping pong balls to model electrons. So for semiconductors, there was either an extra ping pong ball (extra electron) or missing ping pong ball (hole). An empty egg carton was used to represent the conduction band and that was moved further or closer to the valence band depending on whether it was an insulator, conductor or whatever. This represented the energy gap. The electric field and energy supply to create the potential difference were imaginary.

Does that help?