Spin-dependent transport is investigated in a Ni/Ge/AlGaAs junction with an electrodeposited Ni contact. Spin-polarized electrons are excited by optical spin orientation and are subsequently used to measure the spin dependent conductance at the Ni/Ge Schottky interface. We demonstrate electron spin transport and electrical extraction from the Ge layer at room temperature.
Ge is considered to be one of the most promising materials for realizing full monolithic integration of a light source on a silicon (Si) photonic chip. Tensile-strain is required to convert Ge into an optical gain material and to reduce the pumping required for population inversion. Several methods of strain application to Ge are proposed in literature, of which the use of free-standing beams fabricated by micro-electro-mechanical systems (MEMS) processes are capable of delivering very high strain values. However, it is challenging to make an optical cavity within free-standing Ge beams, and here, we demonstrate the fabrication of a simple cavity while imposing tensile strain by suspension using Geon-Insulator (GOI) wafers. Ge micro-disks are made on top of suspended SiO 2 beams by partially removing the supporting Si substrate. According to Raman spectroscopy, a slight tensile strain was applied to the Ge disks through the bending of the SiO 2 beams. Whispering-Gallery-Mode (WGM) resonances were observed from a disk with a diameter of 3 µm, consistent with the finite-domain time-difference simulations. The quality (Q) factor was 192, and upon increasing the pumping power, the Q-factor was degraded due to the red-shift of Ge direct-gap absorption edge caused by heating.
The Random Telegraph Noise (RTN) in an advanced Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET) is considered to be triggered by just one electron or one hole, and its importance is recognised upon the aggressive scaling. However, the detailed nature of the charge trap remains to be investigated due to the difficulty to find out the exact device, which shows the RTN feature over statistical variations. Here, we show the RTN can be observed from virtually all devices at low temperatures, and provide a methodology to enable a systematic way to identify the bias conditions to observe the RTN. We found that the RTN was observed at the verge of the Coulomb blockade in the stability diagram of a parasitic Single-Hole-Transistor (SHT), and we have successfully identified the locations of the charge traps by measuring the bias dependence of the RTN.
We report low-loss silicon waveguides and efficient grating coupler to couple light into them. By using anisotropic wet etching technique, we reduced the side wall roughness down to 1.2 nm. The waveguides were patterned along the
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