{111} and {311} rod-like defects in silicon ion implanted silicon

Rodlike defects in Si ion implantated Si have been studied by transmission electron microscopy and molecular dynamics calculations, Three aspects of these defects are presented here: (1) The defects with (111) habit planes have been identified and the interstitial nature of these defects has been confirmed by matching of the experimental and the calculated images based on the model established by atomistic calculations, (2) The defects with (311) habit planes have complicated high resolution electron microscopy images, This is explained by the coexistence of the Tan model and the Takeda model along an interstitial chain, A bond reconstruction is involved to transform the Tan model into the Takeda model, The energy barrier for this reconstruction is about 1.5 eV. (3) The early stage of the formation of a (011) interstitial chain has been studied by molecular dynamics calculations, when two interstitial atoms form a dimer an interstitial chain with a unit length of the Tan model or the Takeda model is formed, leaving two dangling bonds at two ends promoting other interstitial atoms to stick on to the dimer along the (011) direction

The effect of ion-implantation induced defects on strain relaxation in GexSi1-x/Si heterostructures

This study examined the effect of ion irradiation and subsequent thermal annealing on GeSi/Si strained-layer heterostructures. Comparison between samples irradiated at 253 degrees C with low energy (23 keV) and high energy (1.0 MeV) Si ions showed that damage within the alloy layer increases the strain whereas irradiation through the layer/substrate interface decreases the strain. Loop-like defects formed at the GeSi/Si interface during high energy irradiation and interacting segments of these defects were shown to have edge character with Burgers vector a/2[110]. These defects are believed responsible for the observed strain relief. Irradiation was also shown to affect strain relaxation kinetics and defect morphologies during subsequent thermal annealing. For example, after annealing to 900 degrees C, un-irradiated material contained thermally-induced misfit dislocations, while ion-irradiated samples showed no such dislocations

Deep levels in p(+)-n junctions fabricated by rapid thermal annealing of Mg or Mg/P implanted InP

In this work, we investigate the deep levels present in ion implanted and rapid thermal annealed (RTA) InP p(+)-n junctions. The samples were implanted with magnesium or coimplanted with magnesium and phosphorus. These levels were characterized using deep level transient spectroscopy (DLTS) and capacitance-voltage transient technique (CVTT). Seven majority deep levels located in the upper half of the band gap were detected in the junctions by using DLTS measurements, four of which (at 0.6, 0.45, 0.425, and 0.2 eV below the conduction band) result from RTA, while the origin of the other three levels (at 0.46, 0.25, and 0.27 eV below the conduction band) can be ascribed to implantation damage. An RTA-induced origin was assigned to a minority deep level at 1.33 eV above the valence band. From CVTT measurements, several characteristics of each trap were derived. Tentative assignments have been proposed for the physical nature of all deep levels

Andreev Modes from Phase Winding in a Full-Shell Nanowire-Based Transmon

We investigate transmon qubits made from semiconductor nanowires with a fully surrounding superconducting shell. In the regime of reentrant superconductivity associated with the destructive Little-Parks effect, numerous coherent transitions are observed in the first reentrant lobe, where the shell carries 2{\pi} winding of superconducting phase, and are absent in the zeroth lobe. As junction density was increased by gate voltage, qubit coherence was suppressed then lost in the first lobe. These observations and numerical simulations highlight the role of winding-induced Andreev states in the junction

Magnetic-field-compatible superconducting transmon qubit

We present a hybrid semiconductor-based superconducting qubit device that remains coherent at magnetic fields up to 1 T. The qubit transition frequency exhibits periodic oscillations with the magnetic field, consistent with interference effects due to the magnetic flux threading the cross section of the proximitized semiconductor nanowire junction. As the induced superconductivity revives, additional coherent modes emerge at high magnetic fields, which we attribute to the interaction of the qubit and low-energy Andreev states.QRD/Kouwenhoven LabQuTechBUS/TNO STAF

Controlled dc Monitoring of a Superconducting Qubit

Creating a transmon qubit using semiconductor-superconductor hybrid materials not only provides electrostatic control of the qubit frequency, it also allows parts of the circuit to be electrically connected and disconnected in situ by operating a semiconductor region of the device as a field-effect transistor (FET). Here, we exploit this feature to compare in the same device characteristics of the qubit, such as frequency and relaxation time, with related transport properties such as critical supercurrent and normal-state resistance. Gradually opening the FET to the monitoring circuit allows the influence of weak-to-strong DC monitoring of a live qubit to be measured. A model of this influence yields excellent agreement with experiment, demonstrating a relaxation rate mediated by a gate-controlled environmental coupling