1.Key Laboratory of Infrared Imaging Materials and Detectors， Shanghai Institute of Technical Physics， Chinese Academy of Sciences， Shanghai 200083， China;2.University of Chinese Academy of Science， Beijing 100049， China;3.Hangzhou Institute for Advanced Study， University of Chinese Academy of Sciences， Hangzhou 310024， China
Supported by the National Key Research and Development Program of China (2016YFB0402403),the National Natural Science Foundation of China (NSFC 61974152, 61904183, 61534006， 61505237, 61505235), the Youth Innovation Promotion Association（2016219）, Shanghai Rising-Star Program (20QA141500).
In this work， the surface treatment of InAs/GaSb type-II super-lattice long-wavelength infrared detectors is studied. An optimizing process of N2O plasma treatment and rapid thermal annealing was developed， which can improve the performance of long-wavelength detector with λ50% cut-off=12.3μm from 5.88 ×10-1A/cm2 to 4.09 ×10-2A/cm2 at liquid nitrogen temperature， -0.05V bias. Through variable area device array characterization， the sidewall leakage current was extracted. Under zero bias， the surface resistivity improved from 17.9Ωcm to 297.6 Ωcm. However， the sidewall leakage couldn’t be ignored under large inverse bias after optimizing process， where surface charge might induce the surface tunneling current. It is verified by gate-control structure that there are two main leakage mechanisms in long-wave device： pure sidewall parallel resistance and surface tunneling. At last， the surface charge was calculated to be 3.72×1011cm-2 by IV curve fitting after optimizing process.