In order to identify weapons hidden under the apparel of people walking through entrance gates it is important to use THz illumination of sufficient power levels and fast image detection and processing. The various approaches of THz generation by nanometric dimensions as under studies by the author and his colleagues are described Terahertz quantum cascade lasers (THz QCLs) attracted great attention of many research groups as promising radiation sources for THz imaging, chemical and biological sensing, modulation spectroscopy, heterodyne receivers for astronomy and other applications. Since the first experimental demonstration of a THz QCL laser in 2001 rapid development and progress have been made in the past years. The most frequently reported THz QCL lasers are based on GaAs/AlGaAs, InAs/AlAsSb, GaAs/AlAs material systems and cover the THz range from 1.2 to 5.2 THz . However, these THz QCL devices require cryogenic cooling that limits the area of application of these devices. The maximum operating temperature of ~ 200 K is reported for 3.22 THz QCL based on GaAs/Al0.15Ga0.85As. We proposed the design of ZnSe/ZnMgSe-based terahertz quantum cascade laser structures employing the approach of alternating quantum barriers with variable heights, and with emission frequency of 1.45 THz at room-temperature (300 K) II-VI compounds are attractive as promising materials for the fabrication of roomtemperature devices since they have high breakdown field strengths (~ 331 kV/cm for ZnSe8 vs. ~ 80 kV/cm for GaAs9) and high values of the conduction band offset (CBO), which is about 1.5 eV for a BeSe/ZnSe system in comparison of 0.7 eV for AlAs/GaAs. Moreover, among II-VI compounds, the ZnBeSe/ZnSe and ZnMgSe/ZnSe materials systems are attractive as roomtemperature THz devices, sice these material combinations create a favourable bandgap alignment.