The in‐plane transport properties of a strained (100) Si layer on a relaxed Si_1−xGe_x substrate are studied with an ensemble Monte Carlo technique. Similar velocity (‐field) characteristics are found for strained Si with any valley splitting energy ΔE≥0.1 eV. These phonon‐limited electron mobilities reach 4000 cm²/V s at 300 K, and 23 000 cm²/V s at 77 K. There is only a slight increase in the saturation velocity at both temperatures. However, a significant overshoot peak transient velocity is found to depend upon ΔE, and for ΔE=0.4 eV, reaches 4.1×10⁷ cm/s at 300 K, and 5.2×10⁷ cm/s at 77 K.

In this paper, high-speed surface-illuminated Ge-on-Si pin photodiodes with improved efficiency are demonstrated. With photon-trapping microhole features, the external quantum efficiency (EQE) of the Ge-on-Si pin diode is $>80\%$ at 1300 nm and 73% at 1550 nm with an intrinsic Ge layer of only 2 μm thickness, showing much improvement compared to one without microholes. More than threefold EQE improvement is also observed at longer wavelengths beyond 1550 nm. These results make the microhole-enabled Ge-on-Si photodiodes promising to cover both the existing C and L bands, as well as a new data transmission window (1620–1700 nm), which can be used to enhance the capacity of conventional standard single-mode fiber cables. These photodiodes have potential for many applications, such as inter-/intra-datacenters, passive optical networks, metro and long-haul dense wavelength division multiplexing systems, eye-safe lidar systems, and quantum communications. The CMOS and BiCMOS monolithic integration compatibility of this work is also attractive for Ge CMOS, near-infrared sensing, and communication integration.

It has been suggested by theoretical calculation that indium antimonide (InSb) nanowires can possess improved thermoelectric properties compared to the corresponding bulk crystal. Here we fabricated a device using electron beam lithography to measure the thermopower and electrical conductivity of an individual InSb nanowire grown using a vapor-liquid-solid method. The comparison between the measurement results and transport simulations reveals that the nanowire was unintentionally degenerately doped with donors. Better control of the impurity doping concentration can improve the thermoelectric properties.