LAUSR

This letter reports on the first demonstration of wafer scale flexible InP double heterogeneous bipolar transistors (DHBTs) with record cut-off frequency (f T) and maximum oscillation frequency (f MAX). The as-fabricated DHBTs on 3-inch InP bulk substrate are separated by epitaxial layer lift-off, followed by adhesive bonding onto flexible substrate. Radio frequency measurements reveal that the InP DHBTs on flexible substrate exhibit a f T of 337 GHz and f MAX of 485 GHz, representing the highest f T and f MAX ever reported in flexible electronics. Moreover, InP DHBTs on flexible substrate have good consistency and the functional transistor yield is more than 73%. The results provide ways to accelerate the time for flexible electronics toward future applications working at multi-gigahertz range.