Dark current analysis of long wavelength InAs/GaSb superlattice infrared detector

Dark current characteristics of long wavelength InAs/GaSb superlattice (SL) detectors have been studied in this paper. The long wavelength SL structure consists of periodic 14 monolayers (MLs) InAs and 7 MLs GaSb with 50% cutoff wavelength around 11 mu m. Three InAs/GaSb superlattice detectors of PBIN structure were grown at different temperatures. Wet chemical etching was used to define device mesa. SiO2 was used for device passivation to suppress the sidewall leakage current. Electron barriers were inserted between the absorber region and P-type conducting region to reduce the bulk dark current. The detectors grown at 380 degrees C have the lowest dark current densities as 0.01A/cm(2) and the best R(0)A value as 13 Omega cm(2). We simulated four main dark current mechanisms. The result shows that the intrinsic carrier density is extracted to be 3.5E15 cm(-3) which matches the C-V measurement very well. And the GR and trap assisted tunnel current dominate the dark current of the device due to the large trap densities and short GR lifetimes.