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- 2018
- electron-transparent membranes
- micropump
- field emission electron source
- ion source
- ion mobility spectrometry
- Optoelectronic Information Science and Engineering
- Wroclaw University of Science and Technology
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Improvement of Dupuytren Disease After Treatment With a Fractionated CO2 Laser
摘要： Dupuytren disease (DD) can be a debilitating condition with progressive palmar fibrotic nodule and cord formation with resultant finger flexion deformity. Surgical fasciectomy has been the mainstay of treatment but more recently, intralesional collagenase injection and percutaneous needle fasciotomy or aponeurotomy have proved effective. Recurrences occur in 12% to 73% of cases, with greater risk attributed to those with bilateral disease, a family history of DD, younger age at onset (<50 years), male sex, ectopic disease (outside of the palmar surface), and those from certain ethnicities. Recently, improved function and mobility related to burn scars has been demonstrated through the use of fractionated ablative CO2 lasers. This prompted us to consider this modality in the management of DD, a treatment option that has not been described previously.
关键词： treatment,fractionated CO2 laser,mobility improvement,Dupuytren disease
更新于2025-09-11 14:15:04
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Oxygen vacancy-assisted high ionic conductivity in perovskite LaCoO3? (δ?=?1/3) thin film: A first-principles-based study
摘要： Synthesising a solid state material with high oxygen-ionic conductivity is a challenge. In this work, an integrated method of density functional theory and first-principles molecular dynamics (FPMD) simulations has been performed to investigate the oxygen-ionic conductivity in the LaCoO3?δ films. We demonstrated that, in the strained epitaxial LaCoO3?δ films, O vacancy superstructures release strain and produce the high oxygen-ionic conductivity with an activation barrier of 0.65 ± 0.1 eV. We found that the oxygen hopping occurs in the oxygen-deficient regions of CoO mainly. We proposed a possible oxygen-ionic diffusion highway with an energy barrier of 0.55 eV by using the transition state calculations. Thus, the oxygen-deficient regions are the keys to the high oxygen-ionic conductivity in the LaCoO3?δ thin films.
关键词： Oxygen mobility,First-principles computations,Perovskite LaCoO3,Molecular dynamic simulations,Defects
更新于2025-09-11 14:15:04
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Epitaxial β-Ga2O3 and β-(AlxGa1-x)2O3/β-Ga2O3 Heterostructures Growth for Power Electronics
摘要： We report growth of high quality β-Ga2O3 ?lms using metal organic chemical vapor deposition (MOCVD). Ga(DPM)3, TEGa, and TMGa metal organic precursors were used as Ga sources and oxygen for oxidation. Films grown from each Ga sources had high growth rates with up to 10 μm/h achieved using TMGa. To study the quality homoepitaxial layers, MOCVD was used to grow unintentionally doped (UID) and Si doped β-Ga2O3 layers with a growth rate between 0.5 and 4.0 μm/h Epitaxial layers with XRD FWHM and RMS roughness < 50 arcsec and < 0.5 nm, respectively, were demonstrated. The electron mobility increased from ～13 cm2/Vs for n = 8×1019 1/cm3 to ～120 cm2/Vs for n = 1.6×1017 1/cm3. These values are comparable with the best literature data, despite higher growth rates. For the UID β-Ga2O3 layers, Si was identi?ed as the major impurity responsible for the free carrier concentration with strong accumulation at the ?lm/substrate interface. The reactor was also used to grow high quality strained β-(AlxGa1?x)2O3/β-Ga2O3 heterostructures and superlattices with Al content of up to 43%. The results suggest that the MOCVD enables growth of device quality β-Ga2O3 and related alloys at a fast growth rate which is critical for high voltage power devices.
关键词： electron mobility,β-Ga2O3,MOCVD,β-(Alx, Ga1?x)2O3,growth rates
更新于2025-09-11 14:15:04
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A differential Hall effect measurement method with sub-nanometre resolution for active dopant concentration profiling in ultrathin doped Si <sub/>1?</sub><i> <sub/>x</sub></i> Ge <i> <sub/>x</sub></i> and Si layers
摘要： In this paper, we present an enhanced differential Hall effect measurement method (DHE) for ultrathin Si and SiGe layers for the investigation of dopant activation in the surface region with sub-nanometre resolution. In the case of SiGe, which constitutes the most challenging process, we show the reliability of the SC1 chemical solution (NH4OH/H2O2/H2O) with its slow etch rate, stoichiometry conservation and low roughness generation. The reliability of a complete DHE procedure, with an etching step as small as 0.5 nm, is demonstrated on a dedicated 20 nm thick SiGe test structure fabricated by CVD and uniformly doped in situ during growth. The developed method is finally applied to the investigation of dopant activation achieved by advanced annealing methods (including millisecond and nanosecond laser annealing) in two material systems: 6 nm thick SiGeOI and 11 nm thick SOI. In both cases, DHE is shown to be a uniquely sensitive characterisation technique for a detailed investigation of dopant activation in ultra-shallow layers, providing sub-nanometre resolution for both dopant concentration and carrier mobility depth profiles.
关键词： contact resistance,sub-nanometre resolution,fully depleted silicon on insulator (FDSOI),carrier mobility,differential Hall effect,dopant activation,laser annealing
更新于2025-09-10 09:29:36
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Analytical Study of Electron Mobility in Hemts Algan/Gan
摘要： The hetero junctions GaN based offer an excellent potential for power applications at high frequency. This is due to the important energy of the bandgap and high saturation velocity of electrons. The high mobility transistors (HEMT - High Electron Mobility Transistor) are based on the heterojunction AlGaN/GaN. Our work is the subject of an analytical study of the carrier mobility HEMTs AlGaN/GaN calculating Ionized impurities scattering, Residual impurities scattering, Interface roughness scattering, Alloy disorder scattering, dislocations scattering, Phonons and Dipoles taking into account the impact of technological parameters (doping, aluminium content) and geometric (thickness barrier, interface roughness). The results allowed us to take account of the variation of carrier density in the wells of 2D electronic gas.
关键词： HEMT,Mobility,Scattering mechanism,AlGaN/GaN heterojunction,2DEG
更新于2025-09-10 09:29:36
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Investigation of carrier density and mobility variations in graphene caused by surface adsorbates
摘要： Conductivity, carrier concentration and carrier mobility in graphene were investigated as a function of time in response to ionized donor and acceptor adsorbates. While a reduction in conductivity and hole density in graphene was observed upon exposure to a weak electron donor NH3, the carrier mobility was found to increase monotonically. The opposite behavior is observed upon exposure to NO2, which is expected based on its typical electron withdrawing property. Upon exposure to C9H22N2, a strong donor, it resulted in the transformation of graphene from p-type to n-type, although the inverse variation of carrier concentration and mobility was still observed. The variational trends remained unaltered even after intentional introduction of defects in graphene through exposure to oxygen plasma. The responses to C9H22N2, NH3 and NO2 exposures underline a strong influence by ionized surface adsorbates that we explained via a simple model considering charged impurity scattering of carriers in graphene.
关键词： Carrier density,Gas molecule adsorption,Graphene,Graphene mobility,NH3,NO2
更新于2025-09-10 09:29:36
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Low temperature wet-O <sub/>2</sub> annealing process for enhancement of inversion channel mobility and suppression of <i>V</i> <sub/>fb</sub> instability on 4H-SiC (0001) Si-face
摘要： For improvement of 4H-SiC metal-oxide-semiconductor ?eld-effect-transistor performance, a post-oxidation annealing (POA) process in a wet environment after dry oxidation was systematically investigated. By tuning the wet-POA conditions, we clari?ed that wet-POA at low temperatures is more advantageous for both the enhancement of channel mobility and the suppression of ?atband voltage instability. One of the mechanisms of channel mobility enhancement is attributed to the decrease in the density of traps in oxide near the MOS interface, rather than conventional interface traps. The effects of the wet environment on interfacial properties were also discussed based on oxide growth kinetics on 4H-SiC.
关键词： channel mobility,Vfb instability,MOSFET,4H-SiC,wet-O2 annealing
更新于2025-09-10 09:29:36
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Light-Tuned DC Conductance of Anatase TiO2 Nanotubular Arrays: Features of Long-Range Charge Transport
摘要： Experimental results related to the photoactivated dc conductance of anatase TiO2 nanotubular arrays (aTNTAs) under pulsed irradiation by a laser light inside and outside the fundamental absorption band are presented. It is found that the mobility and diffusion coefficients of charge carriers in the examined aTNTA are extremely low due to a strong charge-phonon coupling, abundance of shallow traps, and hopping conductivity between adjacent nanotubes. We consider that the confining electric field appeared within the array structure due to the difference in the local concentrations of excess electrons and holes at large values of the dc conductance suppresses the drift current. In this case, the dc conductance of such aTNTAs is mainly matured by the diffusion of mobile carriers. A recurrent kinetic model for evolution of the dc conductance of aTNTAs under laser irradiation has been proposed to interpret the experimental results.
关键词： anatase nanotubes,laser irradiation,dc conductance,Urbach energy,drift current,inter-band transition,diffusion current,charge mobility
更新于2025-09-10 09:29:36
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Low-frequency noise in irradiated graphene FETs
摘要： We present a quantitative analysis of the low-frequency noise in irradiated monolayer graphene. In this study, we repeatedly irradiate a back-gated graphene transistor with argon ions at 90 eV and measure its low-frequency noise and channel conductivity after each irradiation. Our results indicate that the noise amplitude decreases monotonically with the increasing density of vacancy defects. The combination of our low-frequency noise measurements and carrier transport studies reveals that the mobility fluctuation model can explain this observation and that the density of vacancy defects, the density of charged impurities, and the mean free path of charge carriers determine the noise amplitude.
关键词： mobility fluctuation model,low-frequency noise,charged impurities,irradiated graphene,vacancy defects,mean free path
更新于2025-09-10 09:29:36
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Growth of Si-doped AlN on sapphire (0001) via pulsed sputtering
摘要： The Si-doped AlN films were grown on sapphire (0001) by pulsed sputtering deposition (PSD), and their structural and electrical properties were investigated. A combination of PSD and high-temperature annealing process enabled the growth of high-quality AlN (0001) epitaxial films on sapphire (0001) substrates with atomically flat stepped and terraced surfaces. The transmission electron microscopy observations revealed that the majority of the threading dislocations in AlN belonged to the mixed- or edge-type, with densities of 2.8 × 108 and 4.4 × 109 cm?2, respectively. The Si-doping of AlN by PSD yielded a clear n-type conductivity with a maximum electron mobility of 44 cm2 V?1 s?1, which was the highest value reported for AlN that was grown on sapphire. These results clearly demonstrated the strong potential of the PSD technique for growing high-quality conductive n-type AlN on sapphire.
关键词： n-type conductivity,Si-doped AlN,pulsed sputtering deposition,electron mobility,sapphire
更新于2025-09-10 09:29:36