  In this paper, mid-wave infrared photodetection based on an InAs/GaSb type-II
superlattice p-i-n photodetector grown directly on Si substrate is demonstrated
and characterized. Excitation power dependence on integrated intensity from the
photoluminescence measurements reveals a power coefficient of P~I0.74,
indicating that defects related process is playing an important role in the
predominant recombination channel for photogenerated carriers. At 70 K, the
device exhibits a dark current density of 2.3 A/cm2 under -0.1 V bias.
Arrhenius analysis of dark current shows activation energies much less than
half of the active layer bandgap, which suggests that the device is mainly
limited by surface leakage and defect-assisted tunneling, consistent with the
photoluminescence analysis. The detector shows 50% cutoff wavelength at ~5.5 um
at 70 K under bias of -0.1 V. The corresponding peak responsivity and specific
detectivity are 1.2 A/W and 1.3*10e9 cm*Hz1/2/W, respectively. Based on these
optoelectronics characterization results, reduction of defects by optimizing
the III/V-Si interface, and suppression of surface leakage channels are argued
to be the main factors for performance improvement in this Si-based T2SL
detector towards low cost, large-format MWIR detection system on Si photonics
platform.
