Development of epitaxial lift-off technique for II-VI semiconductor heterostructures
Eldose, Nirosh M.
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In this thesis, I present current advances with Heriot Watt MBE group II-VI epitaxial lift-off (ELO) technique. Discussing potential structures and devices that can be created using this technology, structures not currently achievable by standard fabrication techniques. ELO is a post growth process which is used to lift off layers grown on the substrate and transfer them to different surfaces. The main advantage of ELO technique is that it can be used to create a new structure by stacking multiple layers and changing the relative orientations of adjacent layers. I present the stacking of ZnSe (1-5 µm) and ZnSe/ZnCdSe single quantum well (QW) structure grown on GaAs (100) and GaAs (211) B substrates. The QW grown structure was lifted off using the highly reactive MgS layer as the sacrificial layer, with etch rate difference of ZnSe of approximately 108 :1 in dilute HCl (30%). The lifted layers were transferred onto a glass plate and stacked 15 layers on top of each other forming a multi quantum well (MQW) structure. The optical characterization was done by photoluminescence (PL) spectroscopy showing no obvious degradation after ELO. Also, the range of structures which can be lifted has been extended further with ZB MgS growth on GaAs (211) B substrates, allowing ELO of (211) ZnSe. This can be used for generating II-VI non-linear quasi phase matched (QPM) devices.