Cryogenic InGaAs HEMTs with Reduced On-Resistance Using Strained Ohmic Contacts

We present InGaAs HEMTs with optimized cryogenic Ohmic contacts, for low-power qubit readout. We utilize tensile strained contact metals to reduce the barrier resistance, which is a major fraction of R SD , leading to ∼50% reduction of R SD at low temperature. At 4 K, a ∼50% lower R ON is shown with tensile strained contacts and demonstrated contact resistance of 30.6 Ω • μm and R ON of 290 Ω • μm at L G = 130 nm, among the lowest reported values for cryogenic HEMT technology. As a result, the InGaAs HEMTs exhibit a record-low value of the noise indication factor$\sqrt {{I_{{\text{DS}}}}} /{g_{\text{m}}} = 0.18\sqrt {{\text{V}}\cdot {\text{mm}}/{\text{S}}} $, at the lowest DC power consumption reported in cryogenic low-noise HEMTs. RF measurements and small-signal model parameters are also presented. The results demonstrate that contact engineering is key to enhance the performance of cryogenic InGaAs HEMTs for future large-scale quantum computing applications.