Compact and fast detectors, for imaging and wireless communication applications, require efficient rectification of electromagnetic radiation with frequencies approaching 1 THz and modulation bandwidth up to a few tens of GHz. This can be obtained only by using a mature technology allowing monolithic integration of detectors with low-noise amplifiers. One of the best candidates is indium phosphide bipolar transistor (InP HBT) technology. In this work, we report on room temperature high sensitivity terahertz detection by InP double-heterojunction bipolar transistors (DHBTs) operating in a large frequency range (0.25-3.1 THz). The performances of the DHBTs as terahertz sensors for communications were evaluated showing the modulation bandwidth of investigated DHBTs close to 10 GHz.

In this paper, three different designs of test structures are explored in order to accurately characterize InP DHBTs up to 110 GHz. In particular, a new design, optimized for high frequency measurements while keeping high device density, has been proposed. De-embedding test structures are analyzed and InP DHBT RF figures of merit are extracted for the three designs. Extraction of the maximum oscillation frequency, fMAX, confirms the relevance of optimized test structures as well as good performances of the new design.