GROWTH OF GERMANIUM-ON-INSULATOR ON SILICON

 

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  Figure : Schematic of fabricated striped array GOI structure

    (a) cross – sectional view and (b) top view W: width, S: spacing

 

 

High quality Ge layers on insulators (GOI) on silicon are promising materials to surpass the performance of the current silicon transistors since the mobility of electrons in germanium is two times greater, and the mobility of holes is 4 times greater than that in silicon . Moreover, GOI structures are also important as channel materials of spin transistors and virtual substrates of direct-band gap materials with optical functions to create multifunctional 3D-LSIs. The high-quality orientation-controlled GOI structures are essential to realise such high-performance electronic and sensing devices and also to act as an epitaxial template for multifunctional 3D-LSIs. In this work, we utilise the Si-seeded rapid-melting growth technique [15]. Here, the Si substrate is used as a seed to induce the lateral growth of Ge, since there is a spatial gradient of the solidification temperature originating as a result of the Si-Ge mixing in the seeding area [Figure above]. Thus far, our study shows that the growth of defect-free single-crystalline Ge stripes (< 5 μm width and μm 0.5 spacing) with a capping layer on the top can be achieved. These preliminary results provide a breakthrough towards the realisation of heterogeneous integration on Si platforms with multi-functionalities.