Study on epitaxial lift-off and Van der Waals bonding of low-temperature grown GaAs

The experimental methods on epitaxial lift-off of 500-run-thick low-temperature molecular beam epitaxy (MBE) grown GaAs (LT-GaAs) epilayers from the substrate on which they were grown, by means of etching out 100-nm-thick AlAs release layer, as well as their Van der Waals bonding on new substrates were studied. Melted black wax was used to the surface of the LT-GaAs in order to protect epilayers during the lift-off, which was also helpful for the outdiffusion of dissolved gas from the etching zone. Proper lift-off dimensions of LT-GaAs for a thickness of 500 nm are given. Experimental techniques are discussed to improve the quality of Van der Waals bonding. Temporal characteristics of photoconductive switches using the epitaxial lift-off LT-GaAs with a structure of coplanar strip transmission line are also given with a rise time less than 1.5 ps, and a full width at half maximum ( FWHM) of less than 2 ps.