Growth study of indium-catalyzed silicon nanowires by plasma enhanced chemical vapor deposition

Indium was used as a catalyst for the synthesis of silicon nanowires in a plasma enhanced chemical vapor deposition reactor. In order to foster the catalytic activity of indium, the indium droplets had to be exposed to a hydrogen plasma prior to nanowire growth in a silane plasma. The structure of the nanowires was investigated as a function of the growth conditions by electron microscopy and Raman spectroscopy. The nanowires were found to crystallize along the , or growth direction. When growing on the and directions, they revealed a similar crystal quality and the presence of a high density of twins along the {111} planes. The high density and periodicity of these twins lead to the formation of hexagonal domains inside the cubic structure. The corresponding Raman signature was found to be a peak at 495 cm−1, in agreement with previous studies. Finally, electron energy loss spectroscopy indicates an occasional migration of indium during growt

Optical study of the band structure of wurtzite GaP nanowires

We investigated the optical properties of wurtzite (WZ) GaP nanowires by performing photoluminescence (PL) and time-resolved PL measurements in the temperature range from 4 K to 300 K, together with atom probe tomography to identify residual impurities in the nanowires. At low temperature, the WZ GaP luminescence shows donor-acceptor pair emission at 2.115 eV and 2.088 eV, and Burstein-Moss band-filling continuum between 2.180 and 2.253 eV, resulting in a direct band gap above 2.170 eV. Sharp exciton α-β-γ lines are observed at 2.140-2.164-2.252 eV, respectively, showing clear differences in lifetime, presence of phonon replicas, and temperature- dependence. The excitonic nature of those peaks is critically discussed, leading to a direct band gap o

Probing Lattice Dynamics and Electronic Resonances in Hexagonal Ge and SixGe1-x Alloys in Nanowires by Raman Spectroscopy

Recent advances in nanowire synthesis have enabled the realization of crystal phases that in bulk are attainable only under extreme conditions, i . e ., high temperature and/or high pressure. For group IV semiconductors this means access to hexagonal-phase Si x Ge 1- x nanostructures (with a 2H type of symmetry), which are predicted to have a direct band gap for x up to 0.5-0.6 and would allow the realization of easily processable optoelectronic devices. Exploiting the quasi-perfect lattice matching between GaAs and Ge, we synthesized hexagonal-phase GaAs-Ge and GaAs-Si x Ge 1- x core-shell nanowires with x up to 0.59. By combining position-, polarization-, and excitation wavelength-dependent μ-Raman spectroscopy studies with first-principles calculations, we explore the full lattice dynamics of these materials. In particular, by obtaining frequency-composition calibration curves for the phonon modes, investigating the dependence of the phononic modes on the position along the nanowire, and exploiting resonant Raman conditions to unveil the coupling between lattice vibrations and electronic transitions, we lay the grounds for a deep understanding of the phononic properties of 2H-Si x Ge 1- x nanostructured alloys and of their relationship with crystal quality, chemical composition, and electronic band structure

Local modification of GaAs nanowires induced by laser heating

GaAs nanowires were heated locally under ambient air conditions by a focused laser beam which led to oxidation and formation of crystalline arsenic on the nanowire surface. Atomic force microscopy, photoluminescence and Raman spectroscopy experiments were performed on the same single GaAs nanowires in order to correlate their structural and optical properties. We show that the local changes of the nanowires act as a barrier for thermal transport which is of interest for thermoelectric applications

Effect of the GaAsP shell on optical properties of self-catalyzed GaAs nanowires grown on silicon

We realize growth of self-catalyzed core-shell GaAs/GaAsP nanowires (NWs) on Si substrates using molecular-beam epitaxy. Transmission electron microscopy (TEM) of single GaAs/GaAsP NWs confirms their high crystal quality and shows domination of the zinc-blende phase. This is further confirmed in optics of single NWs, studied using cw and time-resolved photoluminescence (PL). A detailed comparison with uncapped GaAs NWs emphasizes the effect of the GaAsP capping in suppressing the non-radiative surface states: significant PL enhancement in the core-shell structures exceeding 2000 times at 10K is observed; in uncapped NWs PL is quenched at 60K whereas single core-shell GaAs/GaAsP NWs exhibit bright emission even at room temperature. From analysis of the PL temperature dependence in both types of NW we are able to determine the main carrier escape mechanisms leading to the PL quench

Precision-based exercise as a new therapeutic option for children and adolescents with haematological malignancies

Children and adolescents with haematological malignancies (pedHM) are characterized by a severe loss of exercise ability during cancer treatment, lasting throughout their lives once healed and impacting their social inclusion prospects. The investigation of the effect of a precision-based exercise program on the connections between systems of the body in pedHM patients is the new frontier in clinical exercise physiology. This study is aimed at evaluating the effects of 11 weeks (3 times weekly) of combined training (cardiorespiratory, resistance, balance and flexibility) on the exercise intolerance in PedHM patients. Two-hundred twenty-six PedHM patients were recruited (47% F). High or medium frequency participation (HAd and MAd) was considered when a participant joined; > 65% or between 30% and < 64% of training sessions, respectively. The \u201cup and down stairs\u2019\u2019 test (TUDS), \u201c6 min walking\u201d test (6MWT), the \u201c5 Repetition Maximum strength\u201d leg extension and arm lateral raise test (5RM-LE and 5RM-ALR), flexibility (stand and reach), and balance (stabilometry), were performed and evaluated before and after training. The TUDS, the 5RM-LE and 5RM-ALR, and the flexibility exercises showed an increase in HAd and MAd groups (P < 0.05), while the 6MWT and balance tests showed improvement only in HAd group (P < 0.0001). these results support the ever\u2010growing theory that, in the case of the treatment of PedHM, \u2018exercise is medicine\u2019 and it has the potential to increase the patient\u2019s chances of social inclusion

Comparison of uniportal robotic-assisted thoracic surgery pulmonary anatomic resections with multiport robotic-assisted thoracic surgery: a multicenter study of the European experience

Background: Robotic-assisted thoracic surgery (RATS) has seen increasing interest in the last few years, with most procedures primarily being performed in the conventional multiport manner. Our team has developed a new approach that has the potential to convert surgeons from uniportal video-assisted thoracic surgery (VATS) or open surgery to robotic-assisted surgery, uniportal-RATS (U-RATS). We aimed to evaluate the outcomes of one single incision, uniportal robotic-assisted thoracic surgery (U-RATS) against standard multiport RATS (M-RATS) with regards to safety, feasibility, surgical technique, immediate oncological result, postoperative recovery, and 30-day follow-up morbidity and mortality. Methods: We performed a large retrospective multi-institutional review of our prospectively curated database, including 101 consecutive U-RATS procedures performed from September 2021 to October 2022, in the European centers that our main surgeon operates in. We compared these cases to 101 consecutive M-RATS cases done by our colleagues in Barcelona between 2019 to 2022. Results: Both patient groups were similar with respect to demographics, smoking status and tumor size, but were significantly younger in the U-RATS group [M-RATS =69 (range, 39-81) years; U-RATS =63 years (range, 19-82) years; P<0.0001]. Most patients in both operative groups underwent resection of a primary non-small cell lung cancer (NSCLC) [M-RATS 96/101 (95%); U-RATS =60/101 (59%); P<0.0001]. The main type of anatomic resection was lobectomy for the multiport group, and segmentectomy for the U-RATS group. In the M-RATS group, only one anatomical segmentectomy was performed, while the U-RATS group had twenty-four (24%) segmentectomies (P=0.0006). All M-RATS and U-RATS surgical specimens had negative resection margins (R0) and contained an equivalent median number of lymph nodes available for pathologic analysis [M-RATS =11 (range, 5-54); U-RATS =15 (range, 0-41); P=0.87]. Conversion rate to thoracotomy was zero in the U-RATS group and low in M-RATS [M-RATS =2/101 (2%); U-RATS =0/101; P=0.19]. Median operative time was also statistically different [M-RATS =150 (range, 60-300) minutes; U-RATS =136 (range, 30-308) minutes; P=0.0001]. Median length of stay was significantly lower in U-RATS group at four days [M-RATS =5 (range, 2-31) days; U-RATS =4 (range, 1-18) days; P<0.0001]. Rate of complications and 30-day mortality was low in both groups. Conclusions: U-RATS is feasible and safe for anatomic lung resections and comparable to the multiport conventional approach regarding surgical outcomes. Given the similarity of the technique to uniportal VATS, it presents the potential to convert minimally invasive thoracic surgeons to a robotic-assisted approach.info:eu-repo/semantics/publishedVersio

Unveiling Planar Defects in Hexagonal Group IV Materials

Recently synthesized hexagonal group IV materials are a promising platform to realize efficient light emission that is closely integrated with electronics. A high crystal quality is essential to assess the intrinsic electronic and optical properties of these materials unaffected by structural defects. Here, we identify a previously unknown partial planar defect in materials with a type I 3 basal stacking fault and investigate its structural and electronic properties. Electron microscopy and atomistic modeling are used to reconstruct and visualize this stacking fault and its terminating dislocations in the crystal. From band structure calculations coupled to photoluminescence measurements, we conclude that the I 3 defect does not create states within the hex-Ge and hex-Si band gap. Therefore, the defect is not detrimental to the optoelectronic properties of the hex-SiGe materials family. Finally, highlighting the properties of this defect can be of great interest to the community of hex-III-Ns, where this defect is also present