Visible-extended mid-infrared wide spectrum detector based on InAs/GaSb type-Ⅱ superlattices (T2SL)

The authors report an innovative design of wide spectrum detector that can detect visible and mid-infrared spectrum, from 0.4 to 5 μm, simultaneously. The detector is designed with microstructure of various types of photon traps fabricated on mid-infrared InAs/GaSb type-II superlattice materials. Quantum efficiency has been significantly improved due to the action of photon traps which can decrease the reflectivity of the surface of InAs/GaSb type-Ⅱ superlattice down to less than 5%. Under the condition of 77 K and 200 mV bias voltage, the responsivity of the detector is about 0.025–0.45 A/W in the visible wavelength regime of 400–790 nm, more than 0.3 A/W in spectrum of 800–2000 nm, respectively. Through the optimized photon trap structure, the responsivity of detector is to 1.25 A/W and predominantly improve the quantum efficiency of the detector up to 52.5% at 3 μm.