Low SWaP (size, weight, and power) applications are typical features of thermal imaging systems based on HOT(high operating temperature) detectors. The system performance is comparable to that of a cooled infrared system, with reduced manufacturing costs. They have important application value and are promising prospects for high volume production. The structural features of barrier detectors are introduced, and the structures of the materials used for the barrier detectors and their impact on system performance are analyzed. Other technologies used for HOT detectors are also summarized. Finally, the current research progress on barrier infrared detectors is summarized. Additionally, several future research directions for HOT detector technologies are presented.