InAs-inserted-channel InAlAs/InGaAs inverted HEMTs with NbN electrodes

We report on the fabrication of InAs-inserted-channel InAlAs/InGaAs inverte d HEMTs with NbN electrodes made by using a DC magnetron sputtering deposit ion and we describe the device characteristics we obtained. Excellent pinch -off characteristics were obtained even at similar to 10 K when NbN electro des retain their superconductivity. For a 3-mu m-gate device, the maximum e xtrinsic transconductance at 10 K was 300 mS/mm, even at the very low drain voltage of 0.2 V. We found that the HEMTs with NbN electrodes, not only ha ve superior characteristics at similar to 10 K that exceed the critical tem perature of Nb, but are also able to combine with NbN Josephson junctions.