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on devices of long-term storage at elevated temperatures
without any electrical stresses applied. Purpose of
Stabilization bake is usually to serve as part of a screening
sequence or as a preconditioning treatment prior to the
conduct of other tests. Test condition applied to both sensor
cell and read-out circuit is condition A, specifically 75°C for
24 hours minimum [9].
Last the LTOL (Low Temperature Operating Life) test
was carried out in order to determine the reliability of the
device under low temperature conditions over an extended
period of time. It consists of subjecting the parts to a
specified bias or electrical stressing, for a specified amount
of time, and at a specified low temperature. LTOL test is
documented by JEDEC in a single standards spec, JEDEC
JESD22-A108. Test condition applied to both solar sensor
and read-out circuit is -20 °C for 24 hours minimum [10].
7-9 October 2009, Leuven, Belgium
For the self-made sensor cell we’ve experienced an
average change of 0.24 %/°C in output voltage of the
irradiation sensor (short circuit current of the sensor cell)
Fig. 7. Compared to industrial sensors these values are
almost two times higher (0.15 %/°C), for this reason
comparing spectral response and temperature dependence
measurements with an industrial solar cell (manufactured by
Siemens) were performed.
Observations in case of industrial cell’s temperature
dependence test revealed an average change of 0.11 %/°C in
output voltage Fig. 7. These values correspond to the
parameters given by the industrial irradiation measurement
devices. Based on the measurements performed we could
conclude that the cell’s short circuit current changes not only
according to temperature, but is also influenced by the
structure of the solar cell.
V. DISCUSSION
The circuit’s temperature dependence was studied first.
The reference point is a set output voltage value at T=25°C,
changes that occur will be compared to this value.
5
T=-10°C T=0°C T=10°C T=25°C
T=40°C T=60°C T=80°C
3005
4
Output voltage [mV]
3000
2995
2990
2985
2980
2975
2970
-20 -10 0,2 9,2 20 25 30 40 49,6 59,2 70 80
Temperature [°C]
Short circuit current [mA]
3
2
1
0
392 465 550 622,5 705 790 871,5 1023
Wavelength [nm]
Fig. 6. Temperature dependence of read-out circuit
This resulted in an average output voltage decrease of
0.005 %/°C with temperature Fig. 6.
Afterwards the sensor cell’s temperature dependence was
investigated.
12
Fig. 8. Spectral response of self-made solar cell
T=-10°C T=0°C T=10°C T=25°C
T=40°C T=60°C T=80°C
Uout, Siemens cell [mV]
Uout, our cell [mV]
10
Output voltage [mV]
1800
1700
1600
1500
1400
1300
1200
-20 -10 0 10,2 20 25,5 30 40,6 50 60,5 70,7 80
Temperature [°C]
Short circuit current [mA]
8
6
4
2
0
392 465 550 622,5 705 790 871,5 1023
Wavelength [nm]
Fig. 9. Spectral response of Siemens cell
Fig. 7. Temperature dependence of self-made and Siemens solar cell
The sensor cell made by us is because of the N + substrate,
incorporated to ensure low series resistance, only sensitive
©EDA Publishing/THERMINIC 2009 64
ISBN: 978-2-35500-010-2