申論題

8. Please select "True" of "False" for the following descriptions. (7%)
 (1) In a n-type semiconductor, the number of holes in the valence band is much less than the number of electrons in the conduction band.
(2) In a n-type semiconductor, the current is usually contributed more from electrons than holes.
(3) In a p-type semiconductor, a small amount of an impurity that forms states located in the energy gap close to the edge of the conduction band.
(4) The intrinsic carrier concentration of a certain semiconductor material with bandgap of 0.7 eV is usually smaller than that of a certain semiconductor material with bandgap of 1.I eV at room temperature.
 (5) A certain semiconductor with bandgap of 1 eV is transparent to all visible light.
 (6) The depletion region of a pn junction diode will be located less on the lightly-doped side than the heavily-doped side.
 (7) The tunnel diode will have a larger tunneling current if the doping levels of the pr junction are reduced.