We report on the fabrication and characterization of patterned high mobility two-dimensional electron gases (2DEG) formed on ${\mathrm{SrTiO}}_3$ (STO) substrate surfaces by hydrogen plasma exposure. The resulting devices consistently showed high electron mobilities up to $7400{\mathrm{cm}}^2/\left(\mathrm{V}\mathrm{s}\right)$. A large range of electron density was systematically explored by controlled aging of the sample between cooldowns, including the expected range for the STO 2DEG superconducting dome. No superconducting transition was observed down to the base temperature of approximately 10 mK. This suggests suppression of superconductivity in high mobility quasi-two-dimensional ${\mathrm{SrTiO}}_3$ electron gas, likely linked to vertical confinement and electronic orbital rearrangement. We systematically explored electrostatic gate modulation in this 2DEG system and its scaling with electron density and side gate geometry. In contrast with our initial expectation, we observed an improvement of achievable total modulation for larger side gate to channel separation. At low electron density, stochastic channel pinch-off events were observed, creating quasiballistic constrictions with irregular conductance quantization. This epitaxy-free and high mobility oxide material platform offers a promising route towards patterning quantum devices.

Close

PrevNext

View figure in article

• Ballistic transport
• Superconductivity
• Complex oxides
• Two-dimensional electron gas