A simplified energy band-diagram of an intrinsic semiconductor at thermal equilibrium (300 K) is shown. In the accompanying table, which one of the four cloumns correctly represents the listed parameters? Assume same effective mass for electrons and holes.

Parameter	Energy-difference
	Column 1	Column 2	Column 3	Column 4
Band-gap	ΔE2	ΔE1	ΔE2	ΔE1
Electron affinity	$$\frac{{\Delta {E_1}}}{2}$$	ΔE2 - ΔE1	$$\frac{{\Delta {E_2}}}{2}$$	ΔE2 - $$\left( {\frac{{\Delta {E_1}}}{2}} \right)$$
Work function	ΔE1 + ΔE2	ΔE2 - $$\left( {\frac{{\Delta {E_1}}}{2}} \right)$$	ΔE1 - $$\frac{{\Delta {E_2}}}{2}$$	ΔE2 + $$\left( {\frac{{\Delta {E_1}}}{2}} \right)$$