Terahertz (THz) radiation is of great promise for medical, security and defence imaging applications, etc. However, the lack of sufficiently powerful, compact, reasonably cheap sources and detectors in the 0.3-3 THz range has drastically limited the development of these applications. Conventional THz detection using THz time-domain spectroscopy and heterodyne receivers are power hungry, bulky, extremely expensive and difficult for 2D array formation. THz direct detection has shown advantages to overcome these difficulties. Though a large variety of THz direct detectors have been developed, none of them can work at room temperature (RT) with a high sensitivity. We aim to address the solutions for efficient THz direct detection with a RT, energy efficient and compact solid state source, utilizing the Sb-based heterojunction backward tunneling diodes (HBDs). In theory Sb-HBDs are very promising for efficient THz detection but have not been proved experimentally. The target is to demonstrate HBD receivers that have pW/Hz1/2 sensitivity at RT in the 0.3-1 THz region. We also would like to prove a novel concept to achieve a highly compact energy efficient THz receiver, through monolithic integration of Sb-HBDs and InAs/AlSb HEMTs. Achieving the targeted breakthroughs using compact monolithic devices operating at RT is highly desirable for the THz community and has the potential to create the foundations for long term real-life application-oriented innovation in THz technology.