Question

How do you prove that: (a) holes really exist, (b) holes have a positive charge, (c) Holes have an effective mass?

Answer 1

a) A hole is nothing but vacancy created by electron from moving from one place to other. It is just a vacant place created by electrons. If we consider p type semiconductor then there is large number of vacant places which is nothing but absence of electrons called holes.

b) as we know that holes is a vacancy made by electrons. Hence when a hole is created and a electron is passed through it then that electron will be attracted towards that hole. Therefore a hole is a positive charge particles which attracts electron carrying negative charge.

c) holes are created by electrons therefore mass of the electron and hole will be the same. If we consider silicon material semiconductor then then effective mass of holes and elecrons will be 0.39 and 0.36 in conduction band. Speed of electrons is faster as compared to holes due to low effective mass and presence in conduction band. Hence as holes is vacancy made by electrons therefore it has nearly equal effective mass as elecrons.

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