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Applied Physics A

, Volume 32, Issue 4, pp 187–193 | Cite as

Analytical study of the performance of minSIS solar cells with a back surface field

  • N. R. Saha
  • D. Roychoudhury
  • P. K. Basu
Contributed Papers

Abstract

The effect of a Back Surface Field (BSF) on the performance of a minority-carrier transparent Semiconductor-Insulator-Semiconductor (minSIS) solar cell has been studied. An analytical one-dimensional model has been developed for the calculation of transport characteristics of minSIS solar cells. Short-circuit current, open-circuit voltage, fill factor and efficiency are then calculated for a sputtered Indium-Tin-Oxide (ITO)-SiO2-pSi-p+Si solar cell under AM1 illumination for different values ofpSi- andp+ Si-layer thicknesses. It is found that for a large base thickness, the effect of BSF is not significant; however, for a small thickness all the quantities increase with BSF.

PACS

72.40 86.30J 

Notation

Aa

Top active surface area of the solar cell

c

Velocity of light

Dsp

Density of acceptor-type surface states

Dnl, Dnh

Diffusion coefficient for electrons in the base semiconductor,p+-semiconductor

Eci, Ecs, Ects

Energy of conduction band edge of insulator, base semiconductor, transparent semiconductor

Efps, Efts

Fermi energy level of base semiconductor, transparent semiconductor

Efns

Quasi Fermi level for electrons

Egi, Egs, Egts

Band gap of insulator, base semiconductor, transparent semiconductor

Evi, Evs, Evts

Energy of valence band edge of insulator, base semiconductor, transparent semiconductor

ff

Fill factor

h

Planck's constant

J

Total current density

Jd

Total dark current density

Jn(λ)

Total photocurrent density

Jsc

Short-circuit current density

Jw1n(λ)

Photocurrent density in the depletion layer

Jwpln(λ)

Photocurrent density due to excess electrons in the undepleted base side

k

Boltzmann's constant

Lnh, Lnl

Diffusion length for electrons in thep+-semiconductor, base semiconductor

mte*

Effective mass for electrons in the base semiconductor with momentum transverse to the barrier

npo

Minority carrier electron concentration in neutral layer of base semiconductor in equilibrium

np(x)

Photogenerated minority electron carrier density

np(x1)

Photogenerated minoroty electron carrier density atx1

np(x2)

Photogenerated minority electron carrier density atx2

nph(x3)

Photogenerated electron concentration at the edges ofp-p+ junction

Nah, Nal

Acceptor concentration in thep+-semiconductor, base semiconductor

Ni

Intrinsic carrier concentration in base semiconductor

Nph

Incident photon flux density

Nv

Effective density of states in valence band of base semiconductor

Pin

Input radiant power density

q

Electron charge, absolute value

Qfix+

Fixed positive charges in the interfacial layer

Qsc

Electron charges in the depletion layer 1

Qss

Acceptor-type surface states charges in the interfacial layer

ΔQ′s

Induced surface charge density on the base semiconductor

R*

Modified Richardson constant

Sph

Surface recombination velocity atp-p+ junction

T

Absolute temperature

V

Forward bias

Vb1,Vb2

Built-in potential in the depletion layer1, p-p+ junction at thermal equilibrium

vio vii

Potential drop across the insulator at equilibrium, under illumination

Vi

Change of potential in the insulator due to illumination

Vfns,(x)

Quasi Fermi Potential of electron in the base semiconductor

Voc

Open-circuit voltage

Vpp

Potential drop across thep-p+ junction under illumination

Vph

Change of potential in thep-p+ junction due to illumination

Vs

Applied voltage across thep-base semiconductor

W1,W2

Width of depleted layers at two edge-surfaces ofWpl

Wbpl

Total width ofp-base semiconductor

Wpl

Width of undepletedp-base layer

Wph

Width ofp+-layer

α

Absorption coefficient

Δ

Degree of degeneracy in the transparent semiconductor

δ

Thickness of the insulator

εbi, εs

Permittivity of free space, insulator, base semiconductor

φbpo, φbp

arrier height at equilibrium, under illumination

φe

The value ofΦ e 0 under illumination

φop

Neutral level above which the states are to be filled

φts−i

Potential barrier between the transparent semiconductor and the insulator layer

λ

Wavelength of light

χi−s

Potential barrier between the electron affinityχs of base semiconductor and that of insulator layerχi

η

Conversion efficiency

μnl

Mobility of electrons in thep-base semiconductor

τnl, τnh

Lifetime of minority electron carriers in base semiconductor,p+-semiconductor

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Copyright information

© Springer-Verlag 1983

Authors and Affiliations

  • N. R. Saha
    • 1
  • D. Roychoudhury
    • 1
  • P. K. Basu
    • 1
  1. 1.Centre of Advanced Study in Radio Physics and ElectronicsCalcuttaIndia

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