The effects of fabrication processes on Isc and Voc of monocrystalline silicon solar cell characteristics
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Date
2011
Authors
Hassan Qa'eed, Motahher Abdallah
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Abstract
This thesis is concerned with the fabrication of a solar cell in NOR laboratory
usmg phosphorus and boron diffusions to measure the effect of the fabrication
processes on the mono crystalline silicon solar cell. To carry out this, the researcher
has employed a number of relevant theoretical concepts and equations.
The processes which were performed included thinning the wafer, diffusing
the boron to improve the back surface field (BSF), texturing the surface, diffusing
phosphorus to create the emitter, annealing, anti-reflection coating, metallization, and
edge shunt isolation. KOH solution was used and it played the role of texturing the
surface. Acidic solution was used and it played the role of thinning the wafer.
These processes were measured by easy and direct measurements of short
circuit current (lsc) and open circuit current (Voc). The short circuit current and open
circuit voltage were measured before and after each process, except for thinning the
wafer and (BSF) processes which include two groups of samples the first group is
measured with applying the process. The second group was measured without
applying the process. These electrical measurements were used as the main factors in
this study to examine the solar cell's output. The method of measurement shortens
the measurement time of characterization steps in the laboratory.
In this work, the average of Voc was 345 m V and 415 m V for the thick and
thin « 200 J.1m thick) solar cell respectively; while, the average of lsc for the thick
and thin solar cell was 6.15 rnA and 8.05 rnA respectively. The average Yoc with and
without apply BSF were 163 mY and 360 mY, respectively. Before the metallization
process, the average of Voc was 350 mY. However, it became 398 mV after the
metallization process. The average of Isc was 5.25 mA and 8.13mA before and after
the metallization process, respectively. In this research, the average of Voe before and
after the shunt isolation process was 412m V and 426 m V, respccti vely. While, the
average value of Isc increased from 8.9 rnA to 9.7 rnA due to the shunt isolation
process. The phosphorus diffusion depth in mono crystalline silicon solar cell Xi was
2.457J.Jm. The solar cell efficiency under optimal conditions was 9.51 % and the fill
factor (FF) was 0.79. This work resulted in drawing a clear picture of the electrical
characteristics in each process independently.
Description
Keywords
To measure the effect of the fabrication processes on the , mono crystalline silicon solar cell