Germanium Cell : Germanium Cell

Requires: Blaze/Luminous
Minimum Versions: Atlas 5.28.1.R

This example is a simple demonstration of the application of the transfer matrix method to a simple germanium solar cell.

The cell is a simple P-N germanium photo-diode capped with a InGaP window layer. The simulation enables transfer matrix analysis using the TR.MAT parameter on the BEAM statement.

The example uses the DeckBuild LOOP syntax to loop over wavelengths from 0.6 to 0.7 microns.

This example is illustrative of some of the problems with interpretation of results when using the transfer matrix method on optically thick devices.

If you look at the plot of the spectral response of the device plotted at the end of the simulation, you will see several peaks and valleys in the response. This is a real effect of interference over the whole thickness of the device. The thicker the device the more of these you will see. If you also look at the structure cross-section you will see the intensity also includes numerous peaks and valleys. Here however they appear as random noise. In fact this is an effect of undersampling. The actual result is continuous but the sampling is aliasing against the peaks and valleys to give the apparent noise. In other words the spatial domain is under-sampled. Such noisy results in either the spectral response or the spatial cut plane in very thick devices are usually due to undersampling.

To get rid of this problem you can add the SUBSTRATE parameter to the BEAM statement. This will make the bottom layer "appear" as infinite to the transfer matrix algorithm.

To load and run this example, select the Load button in DeckBuild > Examples. This will copy the input file and any support files to your current working directory. Select the Run button in DeckBuild to execute the example.