Page 242 - 2024-Vol20-Issue2

238 | Ahmed, Alsaif & Algwari

cell simulator’s capacity to calculate the current and character-
istics requires the ability to solve the drift-diffusion equation
for current in a solar cell as illustrated below.
Drift parameter: is the electric field proportional to the veloc-
ity of charged particles. The carrier’s acceleration is frequently
destabilized by collisions with ionized impurity atoms and
thermally vibrating lattice atoms. The drift-current densities
for electrons and holes Jn and Jp drift are described by equa-
tions (6) and (7), respectively, and the overall drift current is
described by equation (8).

Jndri ft = -qnvdn = qnµnE (6) Fig. 1. Structure of standard p-i-n solar cell.

Jpdri f t = qpvd p = qpµpE (7) seed layer (n-type), the base region, i-region, and the emitter
region (p-type), respectively. First and fifth layers were doped
Jdri f t = Jndri f t + Jpdri f t = q.E.(nµn + pµp) (8) with (2x1018 / Cm3) p-type and (1x1018 / Cm3) n-type, re-
spectively, with (50 nm) thickness. The following levels of
Where µn and µp represent the mobility of the electron and doping and thicknesses were utilized for the second, fourth,
hole, respectively. and sixth layers: (500 nm) for p-type doping, (1960 nm) for
Diffusion parameter: is a phenomenon in which, result of n-type doping, and (250 nm) for p-type doping. The i-region
irregular thermal motion, particles tend to spread from high to layer was used, and its thickness was 410 nm. SILVACO
low regions concentration particle. Equations (9) and (10) are TCAD was used to create and simulate the solar cell model.
used to express the diffusion-related currents that are relative
to the gradient in particle concentration, while equation (12) C. Modeling and Simulation of Quantum Dots Solar Cell:
are used to define the total diffusion current [24]. The influence of quantum dots on the performance of the solar
cell was investigated using the same p-i-n structure as before.
Jndi f f . = qDn?n (9) InAs (QDs) were used to fill the intrinsic layer, which is
located between the p-region and the n-region. The structure
Jpdi f f . = qDp?p (10) of p-i-n QDs is shown in Fig. 2, Fig. 3, and Fig. 4. It is
seen that the barrier layers are made of GaAs, and the inserted
quantum dots layer is made up of multiple InAs QDs. The
purpose of the quantum dots utilized is to produce numerous
electron-hole pairs within the intrinsic region, which will
enhance the parameters that determine the features of the
solar cell.

Jdi f f . = Jndi f f . + Jpdi f f . (11)

Jdi f f . = q(pµp + nµn)E + q(Dn?n - Dp?p) (12)

B. Modeling and Simulation of Standard Solar Cell: Fig. 2. ATLAS model of an InGaP/GaAs InAs quantum dot
Fig.1 depicts the p-i-n structure utilized in this simulation solar cell.
as a representation of a solar cell. This model has six lay-
ers, the first and fifth of which are InGaP and are referred to
as the field layer on the rear surface and the window layer,
respectively. Utilizing these two layers has the advantages
of lowering surface recombination at the solar cell’s top and
bottom and blocking minority carriers [6]. GaAs makes up the
second, third, fourth, and sixth layers, which are the epitaxial