High Performance Long Wavelength Superlattice Photodetectors Based on Be Doped Absorber Region

The effect of Be doping on the quantum efficiency and the dark current of InAs/GaSb long-wavelength infrared superlattice photodetectors grown by molecular-beam epitaxy on GaSb substrates are reported. A significant improvement of quantum efficiency (QE) with p-type doping is demonstrated. Our results show that Be doping level at 2.5×10¹⁵ cm³ gives the highest quantum efficiency of product 28%. We also demonstrate that the increased QE is not only resulted from the longer minority carrier diffusion length, but also the p-n junction location change. Finally, the result also shows that the sample with a doping density of 2.5×10¹⁵ cm³ has the largest D^* as 8.68×10¹⁰ cm?Hz^1/2?W^?1, which is almost five times D^* of the non-intentionally doped one.