Environmental Engineering Reference
In-Depth Information
Figure 11.1
Two sets of I-V curves observed for GaAs/AlGaAs-graded
bandgap solar cells.
of open circuit voltages. The first growth of GaAs/AlGaAs system
provided the highest observed
V
oc
values, in the range 1,145-1,175
mV, for single devices. However, the second growth on a GaAs
substrate with a different orientation produced solar cells with
V
oc
valuesintherange840-890mV.ThesetwosetsofI-Vcharacteristics
shown in Fig. 11.1 clearly indicate the appearance of well-defined
and discrete
V
oc
values for GaAs-basedsolar cells.
11.3 Observation of Discrete Sets of
V
oc
Values
Further observations of relevant publications in the literature show
even more striking results. Bauhuis
et al
. [3] carried out similar
workin2007onGaAs-basedsolarcellsandreportedthat
V
oc
values
appear in two different groups. These values appear in the 840-
880 mV or 1005-1045 mV range. Now it is apparent that there
exist at least three groups of well-defined
V
oc
values for GaAs
devicesassummarisedinTable11.1andthisisgraphicallyshownin
Fig. 11.2.
