Prospects for terahertz technology

The interest in wireless local area networks has stimulated considerable research activity at frequencies above 60 GHz. Indeed the idea of exploring the potential bandwidth and propagation properties for carriers in the range 100 GHz to 1 THz has led to increased investment in terahertz technology research. There are now worldwide initiatives across the terahertz frequency range (60 GHz to 10 THz). This activity has prompted a shift in emphasis from detection of terahertz signals (primarily the domain of radio astronomy) to the generation of signals for local oscillators. Simultaneously, this reflects the fact that the biggest challenge facing the development of terahertz technology is the requirement for a solid-state RF sources with useful output power and efficiency, whilst maintaining an acceptable noise performance. This is an essential pre-requisite for the development of compact low power transmitters and receivers. In spite of these difficulties SIS receivers have been built at frequencies up to 600 GHz and oscillators based on semiconductor devices operating in the frequency range 100 to 300 GHz are now widely reported. The paper addresses the prospects for terahertz technology in the context of satisfying the requirements for future communication systems and considers circuits and devices suitable for operation in this frequency regime. It examines the state-of-the-art in semiconductor device technology for terahertz applications and the prospect of monolithic integrated circuit technology for frequencies above 100 GHz