Midwave infrared barrier detector based on Ga-free InAs/InAsSb type-II superlattice grown by molecular beam epitaxy on Si substrate

In this paper, we report on the demonstration of a midwave infrared (MWIR) Ga-free InAs/InAsSb superlattice (SL) barrier detector, grown monolithically on a Si substrate by molecular beam epitaxy (MBE). Prior to the use of MBE, the (1 0 0)-Si substrate was prepared in situ in a metal organic chemical vapor deposition (MOCVD) reactor, where an 800 nm thick GaSb buffer layer was grown. Next, a barrier structure with an active zone made of strain-balanced InAs/InAsSb SL, lattice-matched to GaSb, was epitaxied. Structural characterisations revealed that the material quality was degraded compared with the sample grown on GaSb. The processed Ga-free SL barrier detector has a 100% cut-off wavelength of 5 mu m at 150 K, for a bias operation of -500 mV. A combined analysis involving electrical and electro-optical characterisation was performed to identify the operating regimes in this MWIR Ga-free SL barrier structure.