This chapter focuses on characterization, modeling, and simulation about the type-II superlattices photodetector application. Despite dramatic improvements in type-II superlattices in the past 15 years, challenges still exist in InAs/GaSb and InAs/GaInSb superlattices: The diffusion current, Shockley-Read-Hall (SRH) recombination current, tunneling current, and surface leakage current at elevated temperature. To establish a set of modeling and simulation input parameters, in-depth materials and device characterization at different conditions are carried out for initial materials and device models. Based on input parameters, we will describe the development of analytical and numerical models of InAs/GaSb and InAs/GaInSb type-II superlattice-structured materials and device systems. At the end of this chapter, the fitting of modeled and simulated data will be performed to compare empirical data and modeling results at a set of temperature, which will provide guidance to achieve the higher performance.