Studies of thermally induced transport in nanostructures provide access to an exciting regime where fluctuations are relevant, enabling the investigation of fundamental thermodynamic concepts and the realization of thermal energy harvesters. We study a serial double quantum dot formed in an InAs/InP nanowire coupled to two electron reservoirs. By means of a specially designed local metallic joule-heater, the temperature of the phonon bath in the vicinity of the double quantum dot can be enhanced. This results in phonon-assisted transport, enabling the conversion of local heat into electrical power in a nanosized heat engine. Simultaneously, the electron temperatures of the reservoirs are affected, resulting in conventional thermoelectric transport. By detailed modeling and experimentally tuning the interdot coupling, we disentangle both effects. Furthermore, we show that phonon-assisted transport is sensitive to excited states. Our findings demonstrate the versatility of our design to study fluctuations and fundamental nanothermodynamics.

Hybrid recoil mass analyzer (HYRA) is a unique, dual-mode spectrometer designed to carry out nuclear reaction and structure studies in heavy and medium-mass nuclei using gas-filled and vacuum modes, respectively and has the potential to address newer domains in nuclear physics accessible using high energy, heavy-ion beams from superconducting LINAC accelerator (being commissioned) and ECR-based high current injector system (planned) at IUAC. The first stage of HYRA is operational and initial experiments have been carried out using gas-filled mode for the detection of heavy evaporation residues and heavy quasielastic recoils in the direction of primary beam. Excellent primary beam rejection and transmission efficiency (comparable with other gas-filled separators) have been achieved using a smaller focal plane detection system. There are plans to couple HYRA to other detector arrays such as Indian national gamma array (INGA) and 4π spin spectrometer for ER tagged spectroscopic/spin distribution studies and for focal plane decay measurements.

The separation of hot carriers in semiconductors is of interest for applications such as thermovoltaic photodetection and third-generation photovoltaics. Semiconductor nanowires offer several potential advantages for effective hot-carrier separation such as: a high degree of control and flexibility in heterostructure-based band engineering, increased hot-carrier temperatures compared to bulk, and a geometry well suited for local control of light absorption. Indeed, InAs nanowires with a short InP energy barrier have been observed to produce electric power under global illumination, with an open-circuit voltage exceeding the Shockley-Queisser limit. To understand this behaviour in more detail, it is necessary to establish control over the precise location of electron-hole pair-generation in the nanowire. In this work we perform electron-beam induced current measurements with high spatial resolution, and demonstrate the role of the InP barrier in extracting energetic electrons.We interprete the results in terms of hot-carrier separation, and extract estimates of the hot carriers’ mean free path.

In this study, we have investigated the role of boron nitride nanotubes (BNNTs) on the microstructural and interconnection reliability of a Sn–3.0 wt % Ag–0.5 wt % Cu (SAC305) lead-free solder alloy for microelectromechanical (MEMS) packaging. The BNNT was added in different fractions (0, 0.03, 0.1, 0.2, 0.4, and 0.6 wt %) to a SAC305 molten bath by manual mixing and melting to fabricate a BNNT-decorated SAC305 alloy (B-SAC). We evaluated the effects of BNNTs on the grain morphology, intermetallic compound (IMC) thickness, wetting, and spreading of the SAC305 matrix. The resultant B-SAC alloy was applied to join a 1608 chip to a flip-chip MEMS package, and the joint shear strength of the 1608 chip/Cu pad was studied. The results showed that the B-SAC alloy with 0.4 wt % BNNTs demonstrated finer grains and IMC thickness, a maximum spreading ratio (SR) of 94.08%, least zero-cross time of 0.5 s and surface tension of 224 mN/m, and the highest wetting force (6.95 mN) compared to the pristine SAC305 alloy due to the adsorption of BNNTs into the SAC305 matrix and increment in material fluidity. The joint shear strength of the 1608/Cu pad of the MEMS package also showed maximum improved shear strengthening and fracture energy in B-SAC alloys.

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