First THz and IR characterization of nanometer-scaled antenna-coupled InGaAs/InP Schottky-diode detectors for room temperature infrared imaging

Abstract – Nanometer high performance InP Schottkydetectors are scaled to IR wavelengths. The increasedcutoff frequency of the Schottky detector wasaccomplished by both reducing its capacitance to attofaradrange and also by reducing the contact resistance. TheSchottky detectors were fabricated on InGaAs/InPsubstrates with the doping level as high as 1 x 10 19 cm -2 .The typical Schottky detector anode size was 0.1 x 1 P m 2 .Planar broadband antennas were designed for LWIRwavelengths to couple the radiation into the nanometersize detector. Several different IR antenna designs wereevaluated, including complimentary square spirals, bowties and crossed dipoles . A 6 u 7 array of antenna-coupledSchottky detectors was characterized at DC, yielding a 20 K : zero-bias resistance and a responsivity of 6 A/W forthe entire array. The arrays were characterized at 2.5THz, as well as in the IR (3-5P m and 10.6 P m). The current results for polariza tion sensitivity confirm that anantenna-coupled mechanism i s responsible for themeasured responsivity with the highest value measured at the THz range.