Novel high-breakdown InGaAs/InAlAs pHEMTs for radio astronomy applications

By optimising the epitaxial layer profile of InGaAs-InAlAs pHEMTs we have demonstrated improved DC and RF performance from a new, low-cost, 1 μm-gate device structure in terms of breakdown voltage, leakage current and output conductance. A simple fabrication process is employed that does not use double-recess or composite-channel structures. No penalty was incurred on cut-off frequency or gain due to this new design approach. High uniformity of device characteristics across wafers and between different process runs has been achieved by utilising highly optimised and controlled processing techniques. The room-temperature noise characteristics of these devices are better than 0.5 dB at 1.4 GHz and they show great potential for low-cost, ultra-low-noise LNAs operating at room temperature in the low-frequency radio astronomy band.