Development of epitaxial lift-off technique for II-VI semiconductor heterostructures
Abstract
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.