A new structural approach for uniform sub-micrometer anode metallization of planar THz Schottky components

Abstract

This paper presents the evaluation of a Schottky contact technology based on electrochemical metal deposition. The results of a long-term systematic investigation and optimization of the anode formation process to improve the yield and performance of Schottky-based GaAs mixer diodes are detailed. Surface preparation prior to the Schottky-metal deposition and anode metallization as previously optimized for whisker-contacted diodes are successfully transferred to the fabrication of planar structures. This uses an auxiliary honeycomb array of anode-like structures called 'dummy anodes', which are processed simultaneously with the real anodes and then removed in the later technological processes. Consequently, the scattering of planar diodes electrical parameters is significantly reduced and the yield of the fabrication process increases from about 5% up to about 50%. Very good dc characteristics such as series resistance (R s ) below 8 , ideality factor (η) below 1.2 and saturation current (I sat ) of the order of 10 −17 A are achieved for the anode diameter as small as 1 µm. An excellent IF-noise figure of 250 K at 4.8 GHz up to 280 K at 2.1 GHz with current bias up to 3 mA is obtained for non-cooled THz mixer planar diodes. The use of this technological approach has enabled the extraction of statistically significant data which have been used to characterize the criticality of each step of the fabrication process on the device performance.

Operation of GaN Planar Nanodiodes as THz Detectors and Mixers

“…In order to correctly perform the comparison with experimental measurements, we first calculate the matched MC power per diode, where the IF component is just extracted at (1) Then, the IF power in dBm delivered to a load oscilloscope,…”

“…detectors [1] or THz transistors [2], we report on a unipolar device, known as self-switching diode (SSD). Originally proposed by A. M. Song [3], GaAs-based SSDs have already shown experimentally a good responsivity of 300 V/W at 1.5 THz at room temperature [4]; and noise equivalent power of 65 pW Hz at 110 GHz [5] in the case of InGaAs-based SSDs.…”

Characterisation of a circularly-toothed planar logarithmic-periodic antenna for broadband power detection

“…A planar Schottky diode has been fabricated in GaAs technology [7] and centrally soldered with indium into the waist of the antenna, connecting its two extensions, as shown in Fig. 4.…”

DC- and IF-noise performance optimization of GaAs Schottky diodes for THz applications

“…whisker-contacted or substrate-less [2,13] structure). Additionally this designconcept enables the use of the anode formation technology as-optimized on whisker-contacted diodes, as described in [14] and in more detail in [15]. Therefore, the optimization of the whole technological process of anode fabrication for planar diodes can be first performed on comparatively simple whisker-contacted structures and then applied to the fabrication of planar quasi-vertical structures.…”