SEMICONDUCTOR DEVICE PHYSICS AND DESIGN

380 CHAPTER 8. FIELD EFFECT TRANSISTORS

eφb

EF, m ΔEc

E -eVG

F, s

eV 2

eV 1

eVdi-

• d -ds^0 Δd

eVdi+

Z

Z

nm npar

ns

Nd+

Z

• 1 =-enεm

2 =

ens

ε

• d -ds^0 Δd

(a)

(b)

(c)

(d)

Gate

Metal

{ {

AlGaAs GaAs

δ Layer-doped 2DEG

• d -ds^0 Δd
  dδ
  D

E

E

E(z)

Figure 8.15: (a) Schematic diagram of aδ-doped AlGaAs/GaAs MODFET, along with (b) the
charge distribution, (c) the band diagram, and (d) the electric field distribution in the structure.