Consider the following statements about conditions that make a metal semiconductor contact rectifying

1. N type semiconductor with work function φ_s more than work function φ_M of metal
2. N type semiconductor with work function φ_s less than work function φ_M of metal
3. P type semiconductor with work function φ_s more than work function φ_M of metal
4. P type semiconductor with work function φ_s less than work function φ_M of metal.

Of these statements