Crystalline Ge thin films on glass by Al-induced crystallization

We have looked experimentally into a low temperature (<;400C) Al induced crystallization of amorphous Ge (a-Ge) layers deposited at room temperature on Al coated glass. Here, we have carefully examined the initial nucleation stages and show the critical role of the natively formed aluminum oxide, between the a-Ge and the Al, in driving the Ge crystallization. We have also investigated three different etchant solutions (HCL: H2O (1:10), H3PO4:HNO3:CH3COOH:H2O (16:1:1:4) and dilute HF) for selectively removing Al layer from crystalline Ge after the layer exchange process formed by annealing. We have Ge grain sizes ranging from 25 to 200 μm and further improvement of dominant crystals orientation by the increase of annealing time.