A review of self-assembled monolayers as potential terahertz frequency tunnel diodes

In this review, we describe the principles of the tunnel junction, self-assembled monolayer (SAM) application techniques, experimental testbed fabrication, and characterization of the films and devices. In addition, techniques for directed application, removal, and functionalization of the monolayers are discussed. Bottom-up fabrication techniques have seen increased attention because of their versatility and ease of use. These films see mechanical uses as surface modifiers and micro-scale lubricants. Advances in nanowatt electronics and ultra-low power sensors have opened up an energy harvesting niche for solutions which would have proven ineffective just some years ago. The focus of this study is the two-terminal junction which has potential applications in THz rectification for energy harvesting, medical imaging, and defense sensing. The quantum theory of operation behind these devices is touched on briefly—describing tunneling through the organic monolayers. Commentary on trends in research and potential future work are presented as well.