Transmission Electron Microscopy - Crystal Structure

[happycamper]

Hi

I have a tutorial problem involving determining the ideal methods for identifying material properties of a layered semiconductor structure. The problem states to use either scanning or transmission electron microscopy. THe structure consists of several monolayers (around 5nm) of AlGaAs grown epitaxially on a GaAs substrate. After that, a thicker layer (around 5um) of GaAs is grown on top of the AlGaAs.

I need to a) confirm the materials have identical crystallographic orientation, b) ensure the device has the correct thickness, and c) confirm there is no presence of secondary phases between the layers.

It seems obvious that the TEM has to be used, but from what i have found, the samples need to be no more than about 100nm thick (this sample would be over 5000nm thick). Any help or pushes-in-the-right-direction would be appreciated.

Thanks

 

[Rajini]

Hi,
your sample is called as tandem sample (useful for solar cells i guess!).
yes for TEM samples transparent to electron beam.
Do you know the cross-section sample preparation technique for TEM ?