6.5 Bending of a PN Junction
This section is concerned with PN junctions and bending of beams [6]. We show that
PN junctions with coupling to bending deformation can be realized in properly
constructed composite piezoelectric semiconductor beams. Figure 6.15a shows a
composite beam with a PN junction. For a homogeneous junction the material is
uniform along the beam but the two halves are doped differently. The left half has
more holes and the right half more electrons. For a heterogeneous junction the
materials in the two halves are different. (b) shows the doping profile of an abrupt
junction.
We use the one-dimensional equations derived in Sect. 6.3. The field equations
are from Eqs. (6.83) 1 , (6.87), and (6.89):
Q ,3 ¼ 2b ρ
1
ð Þ h þ ρ
2
ð Þ c
€ u 2 ,
b
D 3,3 ¼ q Δp À Δn
ð
Þ A
2
ð Þ ,
ð6:134Þ
Fig. 6.14 Fields for different values of F. (a) Shear strain S 5 . (b) Axial electric field E 1 . (c) Hole
concentration perturbation. (d) Electron concentration perturbation
168
6 Composite Structures
This section is concerned with PN junctions and bending of beams [6]. We show that
PN junctions with coupling to bending deformation can be realized in properly
constructed composite piezoelectric semiconductor beams. Figure 6.15a shows a
composite beam with a PN junction. For a homogeneous junction the material is
uniform along the beam but the two halves are doped differently. The left half has
more holes and the right half more electrons. For a heterogeneous junction the
materials in the two halves are different. (b) shows the doping profile of an abrupt
junction.
We use the one-dimensional equations derived in Sect. 6.3. The field equations
are from Eqs. (6.83) 1 , (6.87), and (6.89):
Q ,3 ¼ 2b ρ
1
ð Þ h þ ρ
2
ð Þ c
€ u 2 ,
b
D 3,3 ¼ q Δp À Δn
ð
Þ A
2
ð Þ ,
ð6:134Þ
Fig. 6.14 Fields for different values of F. (a) Shear strain S 5 . (b) Axial electric field E 1 . (c) Hole
concentration perturbation. (d) Electron concentration perturbation
168
6 Composite Structures