Solid State Physics Laboratory

About: Solid State Physics Laboratory is a facility organization based out in Delhi, India. It is known for research contribution in the topics: Quantum dot & Dielectric. The organization has 1754 authors who have published 2597 publications receiving 50601 citations.

Tailoring the Band Structure of Twisted Double Bilayer Graphene with Pressure.

Abstract: Twisted two-dimensional structures open new possibilities in band structure engineering. At magic twist angles, flat bands emerge, which gave a new drive to the field of strongly correlated physics. In twisted double bilayer graphene dual gating allows changing of the Fermi level and hence the electron density and also allows tuning of the interlayer potential, giving further control over band gaps. Here, we demonstrate that by application of hydrostatic pressure, an additional control of the band structure becomes possible due to the change of tunnel couplings between the layers. We find that the flat bands and the gaps separating them can be drastically changed by pressures up to 2 GPa, in good agreement with our theoretical simulations. Furthermore, our measurements suggest that in finite magnetic field due to pressure a topologically nontrivial band gap opens at the charge neutrality point at zero displacement field.

Design and fabrication of SOI technology based MEMS differential capacitive accelerometer structure

Abstract: This paper discusses the design and fabrication of MEMS differential capacitive accelerometer (z-axis sensitive) structure. The accelerometer structure consists of one each movable and reference capacitors in the single accelerometer die fabricated using highly conductive (p-type, resistivity: 0.001 Ω cm) SOI substrate. Resonant frequencies of the designed movable and reference capacitive structures were found to be 9.6 kHz and 150 kHz respectively. Corresponding rest capacitance (at 0 g) of both the capacitors was 2.21 pF. The movable and reference structures showed a deflection of 0.14 µm and 0.6 nm respectively at 50 g applied acceleration. Corresponding changes in capacitances of the movable and reference capacitors were 82.3 fF and < 0.33 fF respectively. The designed accelerometer showed a scale factor sensitivity of the movable capacitor was of ~ 1.65 fF/g. The device demonstrated a dynamic range of in − 17 g to 42 g with a full-scale non-linearity of ~ 3%. Corresponding measured scale factor sensitivity in the centrifuge test was found to be ~ 47 mV/g with an acceleration resolution of ~ 17 mg. The device exhibited cross-axis sensitivity of ~ 2% in the full-scale range. Measured 3 dB bandwidth (380 Hz) of the device matches reasonably with the simulated value (~ 400 Hz).