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Number 3026
Application Note Electrical Characterization of
Series Photovoltaic Materials and
Solar Cells with the Model 4200-SCS
Semiconductor Characterization System
I-V, C-V, C-f, DLCP, Pulsed I-V, Resistivity, and
Hall Voltage Measurements
Introduction Making Electrical Measurements
with the Model 4200-SCS
The increasing demand for clean energy and the largely
untapped potential of the sun as an energy source is making To simplify testing photovoltaic materials and cells, the Model
solar energy conversion technology increasingly important. 4200-SCS is supported with a test project for making many of
As a result, the demand for solar cells, which convert sunlight the mostly commonly used measurements easily. These tests,
directly into electricity, is growing. Solar or photovoltaic (PV) which include I-V, capacitance, and resistivity measurements, also
cells are made up of semiconductor materials that absorb include formulas for extracting common parameters such as the
photons from sunlight and then release electrons, causing an maximum power, short circuit current, defect density, etc. The
electric current to flow when the cell is connected to a load. SolarCell project (Figure 1) is included with all Model 4200-SCS
A variety of measurements are used to characterize a solar systems running KTEI Version 8.0 or later. It provides thirteen
cell's performance, including its output and its efficiency. This tests (Table 1) in the form of ITMs (Interactive Test Modules)
electrical characterization is performed as part of research and and UTMs (User Test Modules) for electrical characterization.
development of photovoltaic cells and materials, as well as Table 1. Test modules in the SolarCell project
during the manufacturing process. Subsite Level Test Module Description
IV_sweep fwd-ivsweep Performs I-V sweep and calculates Isc,
Some of the electrical tests commonly performed on solar Voc, Pmax, Imax, Vmax, FF
cells involve measuring current and capacitance as a function rev-ivsweep Performs reversed bias I-V sweep
of an applied DC voltage. Capacitance measurements are CV_sweep cvsweep Generates C-V sweep
sometimes made as a function of frequency or AC voltage. C-2vsV Generates C-V sweep and calculates 1/C2
Some tests require pulsed current-voltage measurements. cfsweep Sweeps the frequency and measures
capacitance
These measurements are usually performed at different light DLCP Measures capacitance as AC voltage is
intensities and under different temperature conditions. A variety swept. DC voltage is applied so as to
keep the total applied voltage constant.
of important device parameters can be extracted from the DC The defect density is calculated.
and pulsed current-voltage (I-V) and capacitance-voltage (C-V) Pulse-IV pulse-iv-sweep Performs pulse I-V sweep using one
measurements, including output current, conversion efficiency, channel of PMU
maximum power output, doping density, resistivity, etc. Electrical 4PtProbe_resistivity HiR Uses 3 or 4 SMUs to source current and
measure voltage difference for high
characterization is important in determining how to make the resistance semiconductor materials.
cells as efficient as possible with minimal losses. Calculates sheet resistivity.
LoR Uses 1 or 2 SMUs to source current and
measure voltage using remote sense.
Instrumentation such as the Model 4200-SCS Semiconductor Calculates sheet resistivity. Uses current
Characterization System can simplify testing and analysis when reversal method to compensate for
thermoelectric voltage offsets.
making these critical electrical measurements. The Model 4200-
vdp_resistivity I1_V23 First of 4 ITMs that are used to measure
SCS is an integrated system that includes instruments for making the van der Pauw resistivity. This ITM
DC and ultra fast I-V and C-V measurements, as well as control sources current between terminals 1 and
4 and measures the voltage difference
software, graphics, and mathematical analysis capability. The between terminals 2 and 3.
Model 4200-SCS is well-suited for performing a wide range of I2_V34 Sources current between terminals 2 and
1 and measures the voltage difference
measurements, including DC and pulsed current-voltage (I-V), between terminals 3 and 4.
capacitance-voltage (C-V), capacitance-frequency (C-f), drive level I3_V41 Sources current between terminals 3 and
capacitance profiling (DLCP), four-probe resistivity (, ), and 2 and measures the voltage difference
between terminals 4 and 1.
Hall voltage (V H) measurements. This application note describes
I4_V12 Sources current between terminals 4 and
how to use the Model 4200-SCS to make these electrical 1 and measures the voltage difference
measurements on PV cells. between terminals 1 and 2.
DC I-V
C-V
Pulsed I-V
Resistivity
Figure 1. Screenshot of SolarCell project for the Model 4200-SCS
DC Current-Voltage (I-V) Measurements Parameters Derived from I-V Measurements
As described previously, many solar cell parameters can be A solar cell may be represented by the equivalent circuit
derived from current-voltage (I-V) measurements of the cell. model shown in Figure 2, which consists of a light-induced
These I-V characteristics can be measured using the Model current source (IL), a diode that generates a saturation current
4200-SCS's Source-Measure Units (SMUs), which can source [IS(eqV/kT