Back-Gated Point Contact

Abstract

This paper presents a micromachined air-gap structure microelectromechanical systems (MEMS) acoustic sensor, which is fabricated via assisted high-speed lateral etching and chemical mechanical polishing (CMP). A sandwich structure (LTO/P 2 O 5 /LTO) as a sacrificial layer for the releasing process is proposed to produce an air-gap structure MEMS acoustic sensor. This sandwich structure can be etched selectively in a specific patterned P 2 O 5 layer. In addition, the sandwich structure proved superior to using only low temperature oxide (LTO) layer for the releasing process. We confirmed that the proposed releasing method assisted by lateral etching and CMP is very effective for creating a clean air-gap cavity in MEMS devices. In this work, the air-gap structure MEMS acoustic sensor is based on the capacitance change of a movable thin poly-silicon membrane. A high-gain impedance converter was mounted on a printed circuit board (PCB) with a silicon MEMS acoustic sensor to transform the electrical signal for input acoustic pressure. The membrane size of the MEMS acoustic sensor was 1.5 × 1.5 mm 2 . The sensitivity achieved was about 0.018-5.17 mV Pa −1 . The noise level of the fabricated device was 10 µV Pa −1 .

Extreme Sensitivity of the Spin-Splitting and 0.7 Anomaly to Confining Potential in One-Dimensional Nanoelectronic Devices

“…3,4 This makes maximizing Figure 5: The precise conductance G of the 0.7 anomaly vs density n for Refs. [26][27][28][29]31,32 and our data from PI-0, PI-375 and BT in Fig. 6.…”

“…This highlights the important role that confinement potential plays in the 0.7 anomaly, and provides an explanation for the conflicting reports regarding the density dependence of the 0.7 anomaly in earlier literature. 17,[24][25][26][27][28][29][30][31][32] We used two different device architectures in this experiment (see Fig. The side-views are sections along the green dot-dashed line.…”

Conductance quantization and zero bias peak in a gated quantum wire

“…In AlGaAs/GaAs quantum point contacts (QPC) conductance plateaus occur at integral values of 2e 2 /h corresponding to an integral number of electric subbands carrying the transport current [1,2]. While integral conductance quantization can be understood from a single-electron picture [3][4][5], the widely observed 0.7 conductance feature observed in QPCs appears to involve manyelectron physics [6][7][8][9][10][11][12][13]. In this paper, we report conductance measurements on a 3 mm long quantum wire with seven cross channel gates.…”

Finite bias conductance of an Anderson level: A source-Liouville Hartree–Fock study

“…Spontaneous spin polarization in quantum systems conducting coherent currents has recently been experimentally observed. [1][2][3][4][5][6][7][8][9][10][11][12] This phenomenon is an important issue for Spintronics, since it may open a possibility to control the spin of a single electron by voltage bias and gate voltage. Apart from this, the theory of this effect attracts recently much interest.…”