Analysis and design of a SiGe-HBT based terahertz detector for imaging arrays applications

Abstract

In this paper, we will introduce a new designed direct conversion terahertz detector and we will compare its characteristics with a prefabricated design in order to obtain better performance of our new proposed design. Differences between our new work and prefabricated device are in both physical structure by introducing an exponentially graded base SiGe-HBT instead of linearly graded ones, and configuration of components by means of merging two transistor of the initial common base structure into a single transistor with two base contacts, which equivalent to two transistors in common emitter configuration. New proposed detector, at first will be analyzed with a compact circuit model and then for more accurate analysis, two dimensional carrier transport analysis will be performed with numerical methods. Comparison of new and prefabricated detector will be done by simulation of both new and prefabricated devices with the same simulator. Because of only a slight change in transistor physical structure, if our simulation results and previous empirical data have a good matching for prefabricated device then with a high degree of precision we can claim our comparison is verified, but of course, for better confirmation of our ideas, fabrication and experimental measurements should be done in the next steps. Responsivity and minimum noise equivalent power of new detector are about 4.9A/W and 6.5pW/Hz1/2 respectively, while these characteristics for prefabricated detector, are about 1A/W and 50pW/Hz1/2 respectively. Also about 231uW/pixel decrement in power consumption for the same responsivity, and a same bandwidth have been achieved.