Fabrication and characterization of cryogenic complementary devices on Si/SiGe heterostructures

We have fabricated cryogenic complementary devices using undoped Si/SiGe heterostructures which contain an electron quantum well and a hole quantum well. The highest temperature in the fabrication process is as low as 440\r{ }C, preserving the quality of the epitaxial films. By properly biasing the gate voltage, two-dimensional (2D) electrons and holes are induced capacitively in the quantum wells. The electron mobility, $\sim $2$\times $10$^{4}$ cm$^{2}$/Vs, is significantly lower than that in a heterostructure without any hole quantum well. Nevertheless, the induced 2D electrons show the integer and fractional quantum Hall effect characteristics. The mobility of the 2D holes is $\sim $7$\times $10$^{3}$ cm$^{2}$/Vs, consistent with previous reports, and is limited by alloy scattering. A proof-of-principle inverter is demonstrated.