Wideband AlN-based SIS devices for frequencies around 700 GHz

We report results on SIS tunnel junctions based on AlN tunnel barriers grown with plasma nitridation from a remote inductively coupled plasma source. Results for the noise temperature are shown and compared to AlOx results in a ALMA Band 9 mixer. The parameters for AlOx devices are RnA=25 Ωμm with a normal state resistance of 25 Ω and an optimized tuning circuit. For the AlN devices we have RnA = 2.9 Ωμm (Jc=71kA/cm), A=0.36 μm, Vgap=2.77 mV, and Rsg/Rn = 14. The data for AlN devices with a not yet optimized tuning circuit show comparable noise temperatures and a flat noise response.