Surface conductivity of InAs/GaSb superlattice infrared detectors treated with thiolated self assembled monolayers

摘要

The surface conductivity of InAs/GaSb based type Ⅱ superlattice (T2SL) long wavelength infrared material following the deposition of thiolated self-assembled monolayers (SAMs) of cysteamine, octadecanethiol, dodecanethiol, and hexanethiol are reported. Quantitative mobility spectrum analysis (QMSA) was employed to study the mobility and to isolate and identify surface carriers following SAM treatments on planar samples. QMSA data collected following the deposition of the SAMs on InAs/GaSb material correlates well with dark current measurements, demonstrating the usefulness of QMSA as a tool for evaluating surface conductivity and predicting device performance. All samples displayed a reduction in surface conductivity and dark current density following thiol treatment. Dark current densities were reduced to 1.1 × 10~(-5), 1.3 × 10~(-5), 1.6 × 10~(-5), and 5 × 10~(-6) A/cm~2 for hexanethiol, dodecanethiol, octadecanethiol, and cysteamine, respectively, from 5.7 × 10~(-4) A cm~2 for unpassivated devices.