SLIDE 1
PVMD
Delft University of Technology
Crystalline silicon solar cell
p-type c-Si absorber n-type c-Si
depletion region
back contact front contact p++-type c-Si
depletion region
PVMD Miro Zeman Delft University of Technology Crystalline silicon - - PowerPoint PPT Presentation
PVMD Miro Zeman Delft University of Technology Crystalline silicon - - PowerPoint PPT Presentation
The Depletion Region PVMD Miro Zeman Delft University of Technology Crystalline silicon solar cell front contact n-type c-Si depletion region p-type c-Si absorber depletion region p ++ -type c-Si back contact Learning objectives
SLIDE 2
SLIDE 3
Learning objectives
▪ Thermal equilibrium properties of P-N junction ▪ What is the depletion region? ▪ How is the depletion region formed? ▪ Why is there an internal electric field in the depletion region?
SLIDE 4
Isolated doped silicon
Charge neutral Charge neutral n-type Si p-type Si
SLIDE 5
P-N junction at thermal equilibrium
metallurgical junction n-type Si p-type Si
SLIDE 6
P-N junction at thermal equilibrium
ND = 1018 cm-3 p ≈ 102 cm-3 n = 1018 cm-3 NA = 1016 cm-3 p = 1016 cm-3 n ≈ 104 cm-3
> <
Standard c-Si solar cells n-type Si p-type Si
SLIDE 7
P-N junction at thermal equilibrium
diffusion ND = 1018 cm-3 p ≈ 102 cm-3 n = 1018 cm-3 NA = 1016 cm-3 p = 1016 cm-3 n ≈ 104 cm-3
> <
n-type Si p-type Si Standard c-Si solar cells
SLIDE 8
P-N junction at thermal equilibrium
Depletion region
Quasi-neutral region qND ρ x
qNA qND
Quasi-neutral region
diffusion n-type Si p-type Si
SLIDE 9
P-N junction at thermal equilibrium
Quasi-neutral region qND ρ x
qNA qND
Quasi-neutral region
diffusion drift
Depletion region
n-type Si p-type Si
SLIDE 10
P-N junction at thermal equilibrium
Quasi-neutral region Quasi-neutral region