MOVPE-grown millimeter-wave InGaAs mixer diode technology and characteristics

The merits of InGaAs-based millimeter-wave mixer diodes are explored experimentally and theoretically. Schottky junctions on InGaAs exhibit barriers (φ_b) in the neighborhood of 0.25 eV. The high mobility of InGaAs contributes to the low n⁺ sheet resistances of 1.9-5 Ω/square for 1-μm n⁺ InGaAs layers (n_s=1.5×10¹⁹ cm^-3, μ _n=1800 cm²/V·s) grown with our in-house Metalorganic Vapor Phase Epitaxy (MOVPE) system, The design, material growth, fabrication, and characterization of InGaAs integrated mixer/antennae are reported. Pt plating technology, adapted here for InGaAs Schottky contacts, has improved the ideality factor (η) and yield relative to conventional evaporated Pt. With 810 μW of local oscillator power, applied to the diode, and zero DC bias, an integrated InGaAs mixer/antenna demonstrated an excellent diode performance of 199 K RF input double-sideband noise temperature with a corresponding single-sideband (SSB) conversion loss (L_c) of 5.0 dB at LO, RF, and IF frequencies of 94 GHz, 94 GHz±1.4 GHz, and 1.4 GHz, respectively. Likewise, the diodes in an InGaAs subharmonic integrated mixer/antenna demonstrated an equivalent RF-port double-sideband (DSB) noise temperature (T_mix) of 1058 K and single-sideband conversion loss of 10.2 dB at 180 GHz with a 90-GHz LO power (PLO) of 1.6 mW. Compared to GaAs diodes with RF coupling and IF losses removed, the single-ended InGaAs noise temperature results were within 46-100 K of those for state-of-the-art GaAs mixer diodes while requiring significantly less LO power