Surface illuminated InAs photodiodes 3.0-3.3 mm

Basic parameters at t=20 ⁰C

InAs photodiodes with InAsSbP transparent window layer, operating in the wavelength range 1.0-4.0 µm are based on InAsSbP/InAs and systems that is lattice matched and hence low defect density and high performance are expected. Heterostructures were grown by the LPE method on a 350 µm thick n-InAs substrates (n=2*10¹⁶cm^-3) and processed by a wet photolithography into a mesa constructions.

The quaternary layer InAsSbP acts as a window because the larger bandgap material is transparent to 3 µm radiation and thus most of the light is absorbed in the active region of the device. The composition of the widegap layer determines the short-wavelength cut-off value and the active region composition establishes the long-wavelength cut-off value of spectral response. One advantage of this structure is the relative independence of the quantum efficiency on the distance of the junction from the illuminated surface. Another advantage is that the heterostructure can offer a reduced dark current because the wider bandgap layer usually has a lower equilibrium concentration of minority carriers which contribute to the diffusion current.

The diodes can be coupled with micro immersion lenses.

Dimensions of typical headers

p-InAsSbP/n-InAs photodiode section view. 1- InAsSbP window layer, 2-InAs substrate, 3-cathode, 4-anode