For the given circuit of p-n junction diode which is correct

In a p-n junction

The given truth table is for which logic gate

              $$\matrix{ A & B & Y \cr 1 & 1 & 0 \cr 0 & 1 & 1 \cr 1 & 0 & 1 \cr 0 & 0 & 1 \cr } $$

Number of atom per unit cell in B.C.C.