Sulfurizing Method for Passivation Used in InAs/GaSb Type-II Superlattice Photodetectors

Since InAs/GaSb type-II superlattices (T2SL) were first proposed as infrared (IR) sensing materials, T2SL mid-wave IR (MWIR) and long-wave IR (LWIR) are of great importance for a variety of civil and military applications. A very important parameter of IR photodetectors is dark current, which affects the detectivity directly. Chemical and physical passivation has revealed to be an efficient technique to reduce surface component of dark current, which will become a dominant current in focal plane arrays (FPA). In this paper we talk about the electrochemistry and dielectric method for passivation. We choose anodic sulfide and SiO2 passivation. The leakage current as a function of bias voltage (I-V) results show dark current of anodic sulfide device was two orders of magnitude lower than unpassivation one, but reactive magnetron sputtering SiO2 didn't perform well. The highest R(0)A we get from the sulfurizing experiment is 657 Omega.cm(2) in 77K. After fabrication the measured cutoff wavelength is 5.0 mu m. Finally blackbody test result shows that the peak quantum efficiency (QE) at 3.33 mu m is 68% and the peak detectivity is 7.16x10(11)cm.Hz(1/2)/W.