Antimonide-based superlattice membranes for infrared applications

Semiconductor membranes offer an interesting materials and device development platform due to their ability to integrate dissimilar materials through a print, stamp and transfer process. There is a lot of interest in integrating antimonide based type-II superlattices (T2SL) onto inexpensive substrates, such as Si, to not only undertake fundamental studies into the optical, electronic and structural properties of the superlattices but also to fabricate wafer-level infrared (IR) photodetectors. An effective approach to transfer type-II superlattice membranes (T2SL-M) onto alternate substrates is based on membrane release from the native GaSb substrate followed by the transfer to a new host substrate. In this work, I have transferred InAs/GaSb and InAs/InAsSb T2SLs with different in-plane geometries from a GaSb substrate to a variety of host substrates, including Si, polydimethylsiloxane and metal coated surfaces. Electron microscopy shows structural integrity of transferred membranes with thicknesses ranging from 100 nm to 2.5 µm and lateral sizes from 24x24 µm2 v to 1x1 cm2 . Atomic force and electron microscopy reveal the excellent quality of the membrane interface with the new host. The crystalline structure of the membrane is not altered by the fabrication process, and minimal elastic relaxation occurs during the release step, as demonstrated by X-ray diffraction and mechanical modeling. I have also used the antimonide superlattice membranes to realize wafer level infrared detectors on silicon substrates without using conventional Indium-bump hybridization. In this approach, PIN superlattices are grown on top of a 60 nm Al0.6Ga0.4Sb sacrificial layer on a GaSb host substrate. Following the growth, I have transferred the individual pixels using an epitaxial lift-off technique, which consists of a wet-etch to undercut the pixels followed by a dry-stamp process to transfer the pixels to a silicon substrate prepared with a gold layer. I have done structural and opt