Type-II InAs/GaSb superlattice grown on InP substrate

Mid-infrared Type-II InAs/GaSb Superlattice Photodiodes Fabricated on InP Substrates

“…The strong PL intensity of the SL on the InP substrate seems to be contradictory to the fact that threading dislocations are found to be generated at the initial stage of the GaSb buffer layer growth and propagate to the SL in a previous study. (10) The reason is not clear yet. However, the authors suppose that the strong excitation density (7076 W/cm 2 ) weakens the influence of the threading dislocations.…”

“…In a previous study, threading dislocations are found to be generated at the initial stage of the GaSb buffer layer growth and propagate to the SL. (10) It is inferred that the dark current of the PD on the InP substrate is generated by the threading dislocations. Suppression of threading dislocation in the SLs is necessary.…”

“…The In 0.53 Ga 0.47 As layer is effective in making the surface smooth, and the thick GaSb buffer layer is effective in reducing the propagation of threading dislocations into the SL. (10) The doping density in the GaSb buffer layer is 2.0 × 10 18 cm −3 . InAs/GaSb SL, which consists of 100 pairs of 3.7-nm-thick InAs and 2.1-nm-thick GaSb, was grown on the GaSb buffer layer.…”

“…The GaAs also has the problem that the large lattice mismatch between GaAs and GaSb (7.8%) makes the epitaxial growth difficult. (8,9) InP substrates are more favorable because of not only a high transparency in the midinfrared region but also a smaller lattice mismatch to the GaSb as listed in Table 1 (10) By using a thicker GaSb buffer layer on the InP substrate, the full width at half maximum of X-ray satellite peaks and the photoluminescence intensities were improved. In this study, mid-infrared PDs with InAs/GaSb SL absorption layers grown on InP substrates were successfully fabricated for the first time.…”