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The technology of arranging particles by ultrasound has matured. In recent years, this technology has been used as a basis for arranging particles in a photocurable resin for stereolithography (SL). In order to process the resin doped with particles to obtain a variety of particle arrangement patterns, most of the previous work chose to use different polygonal containers to obtain single-layer fiber angles. In this adjustment mode, the selectivity of the fiber angle is very poor, usually 45°, 90° and other common angles. In this work, we designed and manufactured a new ultrasound-assisted 3D printing platform that can flexibly adjust the thickness of the sandwich and the rotation angle of the sandwich. We will introduce the basic working principle and matching usage of the device, and show some basic print samples.

A Green's-function approach is employed to calculate the electron tunneling through a double-barrier device for infrared-radiation detection. Electrons photoexcited by an ir beam undergo transitions to a resonant channel, so that the transmission coefficient for tunneling substantially increases by several orders of magnitude compared with the dark state. This photon-induced resonant tunneling can be switched and controlled by a change of the applied static voltage. Such a system is ideal for ir photodetectors.

We study the transport of the photoexcited quasi-2D electron-hole (e-h) plasma in a p-doped semiconductor quantum well, where electrons are a minority. Using the drifted temperature model for both electrons and holes and introducing a coordinate transformation to the center-of-mass system, separately, for electrons and holes, we obtain a set of coupled equations for the drift velocities and the temperatures of electrons and holes. We show that negative absolute mobility for minority electrons occurs at low temperature and under a weak electric field due to the electron-hole drag. In a strong electric field and at room bath temperature, our results show that the electrons are heated much more than the holes. The electron mobility is smaller in the presence of the hole plasma than in the absence of holes. These results are in agreement with experiments.