InGaAs-Schottky contacts made by in situ plated and evaporated Pt-an analysis based on DC and noise characteristics

The choice of plated versus evaporated Pt Schottky anode formation technology is shown to have a significant impact on junction quality and the noise temperature of InGaAs mixer diodes. The investigated diode layers were grown in-house via Metalorganic Vapor Phase Epitaxy (MOVPE) on an S.I. InP wafer. For anode diameters at and below 2 μm, plated anodes clearly show superior fabrication (~80%) yields relative to evaporated (below ~5%). DC and low-/high-frequency noise characteristics were compared, as functions of DC current drive, for plated versus evaporated InGaAs Schottky contacts at 10 Hz-100 kHz and 1.4 GHz for 4- and 6- μm anode diameters. Plated anodes show distinctly lower ideality factors of ~1.2 versus ~1.4-1.66 for evaporated anodes. Plated Schottky contacts showed 5.5 dB lower noise levels in the range of 10 Hz-100 kHz and a lower noise temperature (220 K versus 360 K) at 1.4 GHz. Overall, relative to conventional evaporated Pt, plated Pt anode technology offers superior fabrication yield and should lead to higher receiver sensitivity especially when low IF frequencies are used