SEMICONDUCTOR DEVICE PHYSICS AND DESIGN

5.3. METAL SEMICONDUCTOR JUNCTION: SCHOTTKY BARRIER 221

n-type or p-type

semiconductor

Metal

≈ ≈

φm > φs n-type

Ec

EFs

n-semiconductor

Metal

EFm

(a)

Vacuum energy

Ev

METAL-SEMICONDUCTOR JUNCTION AT EQUILIBRIUM

eφs eχs

eφm

(b)

(c)

Ec

EFs

Ev

EFm

eφm – eφs = eVbi

W

eφm eφb

eχs

Vacuum energy

Figure 5.2: (a) A schematic of a metal-semiconductor junction. (b) The various important energy
levels in the metal and the semiconductor with respect to the vacuum level. (c) The junction
potential produced when the metal and semiconductor are brought together. Due to the built-in
potential at the junction, a depletion region of widthWis created.