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.

Spin-orbit interaction and spin relaxation in a two-dimensional electron gas

Abstract: Using time-resolved Faraday rotation, the drift-induced spin-orbit field of a two-dimensional electron gas in an InGaAs quantum well is measured. Including measurements of the electron mobility, the Dresselhaus and Rashba coefficients are determined as a function of temperature between 10 and 80 K. By comparing the relative size of these terms with a measured in-plane anisotropy of the spin-dephasing rate, the D'yakonov-Perel' contribution to spin dephasing is estimated. The measured dephasing rate is significantly larger than this, which can only partially be explained by an inhomogeneous $g$ factor.

Optical, Electrical and Morphological Studies of SnSe2 Crystals Grown by Physical Vapour Transport Method

Abstract: Tin diselenide single crystals have been grown by the physical vapour transport (PVT) method. Optical absorption studies give an indirect allowed transition at 1.03 eV at room temperature. The electrical resistivity parallel and perpendicular to c-axis, mobility and carrier concentration have been determined. Dependence of resistivity parallel to c-axis on temperature gives an activation energy of 0.072 eV. Growth spirals observed for the first time on the as grown faces of these crystals are also presented here.

The Oxide Film-Coated Surface Acoustic Wave Resonators for the Measurement of Relative Humidity

Abstract: The surface acoustic wave (SAW) humidity sensor may possess many attractive sensing characteristics such as high sensitivity, high resolution, high stability, frequency output, ease of interfacing, small size, and broad dynamic range. Mostly, the polymer materials are used for the SAW humidity sensor fabrication. But the polymer SAW sensors suffer from broad bandwidth, instability due to ambient temperature, nonlinearity, and small dynamic range. This article presents the fabrication of metal oxide film humidity sensors using SAW resonators of 433.92-MHz frequency. Five different SAW humidity sensors were fabricated by varying the deposited alumina film thickness to measure humidity in the range of 0%–98% relative humidity (RH). The hydrophilic films were formed by dip coating of alumina solution of different molar concentrations. The alumina film is thermally stable and inert. The static and dynamic response characteristics were determined from the shift in resonant peaks at different humidity using an HP 85046A vector network analyzer (VNA). The minimum sensitivity of the least sensitive sensor was found to be 2.51 kHz/%RH. The sensors show linear response ( $R^{2} \ge0.98$ ), high sensitivity (max. ~ 9 kHz/%RH), negligible hysteresis error (≤0.50%), wide dynamic range, and inexpensive fabrication due to the use of commercial resonators. The response parameters of the sensors were compared with the parameters of other oxide SAW sensors reported in the literature. Finally, the linear sensor was interfaced to the electronic and associated signal conditioning circuits to display humidity in %RH.

Towards electron transport measurements in chemically modified graphene: effect of a solvent

Abstract: The chemical functionalization of graphene modifies the local electron density of carbon atoms and hence electron transport. Measuring these changes allows for a closer understanding of the chemical interaction and the influence of functionalization on the graphene lattice. However, not only chemistry, in this case diazonium chemistry, has an effect on electron transport. The latter is also influenced by defects and dopants resulting from different processing steps. Here, we show that the solvents used in the chemical reaction process change the transport properties. In more detail, the investigated combination of isopropanol and heating treatment reduces the doping concentration and significantly increases the mobility of graphene. Furthermore, isopropanol treatment alone increases the concentration of dopants and introduces an asymmetry between electron and hole transport, which might be difficult to distinguish from the effect of functionalization. The results shown in this work demand a closer look at the influence of solvents used for chemical modification in order to understand their influence.