Search results for "puolijohteet"
showing 10 items of 27 documents
Facile fabrication of flower like self-assembled mesoporous hierarchical microarchitectures of In(OH)3 and In2O3: In(OH)3 micro flowers with electron…
2016
Abstract A template and capping-reagent free facile fabrication method for mesoporous hierarchical microarchitectures of flower-like In(OH) 3 particles under benign hydrothermal conditions is reported. Calcination of In(OH) 3 to In 2 O 3 with the retention of morphology is also described. Both In(OH) 3 and In 2 O 3 microstructures were analyzed with SEM, EDX, TEM and powder X-ray diffraction. The crystal sizes for In(OH) 3 and In 2 O 3 were calculated using the Scherrer equation. In In(OH) 3 the thin flakes at the periphery of micro flowers were electron beam sensitive. The mechanism of self-assembly process was analyzed as well.
Solvent-mediated assembly of atom-precise gold–silver nanoclusters to semiconducting one-dimensional materials
2020
Bottom-up design of functional device components based on nanometer-sized building blocks relies on accurate control of their self-assembly behavior. Atom-precise metal nanoclusters are well-characterizable building blocks for designing tunable nanomaterials, but it has been challenging to achieve directed assembly to macroscopic functional cluster-based materials with highly anisotropic properties. Here, we discover a solvent-mediated assembly of 34-atom intermetallic gold–silver clusters protected by 20 1-ethynyladamantanes into 1D polymers with Ag–Au–Ag bonds between neighboring clusters as shown directly by the atomic structure from single-crystal X-ray diffraction analysis. Density fun…
Mikrokokoistetut leviämisvastus- ja nelipisteanturimittaukset puolijohderakenteen varauksenkuljettajien syvyysjakaumien määrittämisessä
2013
Entistä pienemmät puolijohderakenteet vaativat analyysityökaluilta erittäin hyvää herkkyyttä, jonka on myös kehityttävä rakenteiden vaatimusten mukaisesti -- muussa tapauksessa kehitys voi hidastua hyvin paljon ilman kunnollista tietoa valmistusmenetelmien tuloksista. Yksi oleellinen osa rakenteiden analysoimisessa on tieto seostusatomien ja varauksenkuljettajien pitoisuuksista rakenteen syvyyssuunnassa, eli syvyysjakauma. Vuosikymmeniä syvyysjakauman mittaukseen on käytetty leviämisvastusmittausta (SRP, engl. Spreading Resistance Profiling), ja nelipisteanturimittausta (4PP, engl. Four Point Probe) on käytetty kuvaamaan koko syvyysjakauman vaikutusta sähköisessä kontaktissa. Molempien tekn…
Improved stability of black silicon detectors using aluminum oxide surface passivation
2021
Publisher Copyright: © 2021 ESA and CNES We have studied how high-energy electron irradiation (12 MeV, total dose 66 krad(Si)) and long term humidity exposure (75%, 75 °C, 500 hours) influence the induced junction black silicon or planar photodiode characteristics. In our case, the induced junction is formed using n-type silicon and atomic-layer deposited aluminum oxide (Al2O3), which contains a large negative fixed charge. We compare the results with corresponding planar pn-junction detectors passivated with either with silicon dioxide (SiO2) or Al2O3. The results show that the induced junction detectors remain stable as their responsivity remains nearly unaffected during the electron beam…
Heavy-ion induced single event effects and latent damages in SiC power MOSFETs
2022
The advantages of silicon carbide (SiC) power MOSFETs make this technology attractive for space, avionics and high-energy accelerator applications. However, the current commercial technologies are still susceptible to Single Event Effects (SEEs) and latent damages induced by the radiation environment. Two types of latent damage were experimentally observed in commercial SiC power MOSFETs exposed to heavy-ions. One is observed at bias voltages just below the degradation onset and it involves the gate oxide. The other damage type is observed at bias voltages below the Single Event Burnout (SEB) limit, and it is attributed to alterations of the SiC crystal-lattice. Focused ion beam (FIB) and s…
Temperature dependence of recombination radiation in semiconductor nanostructures with quantum dots containing impurity complexes
2021
Temperature dependence of the spectral intensity of recombination radiation in a quasi-zero-dimensional structure, containing impurity complexes “A++e” (a hole localized on a neutral acceptor, interacting with an electron localized in the ground state of a quantum dot), has been investigated in an external electric field in the presence of tunneling decay of a quasistationary A+-state. Probability of dissipative tunneling of a hole has been calculated in the one-instanton approximation, and the influence of tunneling decay and of an external electric field on the A+-state binding energy and on the spectra of recombination radiation, associated with the optical transition of an electron from…
Plasmon-Induced Direct Hot-Carrier Transfer at Metal-Acceptor Interfaces.
2019
Plasmon-induced hot-carrier transfer from a metal nanostructure to an acceptor is known to occur via two key mechanisms: (i) indirect transfer, where the hot carriers are produced in the metal nanostructure and subsequently transferred to the acceptor, and (ii) direct transfer, where the plasmons decay by directly exciting carriers from the metal to the acceptor. Unfortunately, an atomic-level understanding of the direct-transfer process, especially with regard to its quantification, remains elusive even though it is estimated to be more efficient compared to the indirect-transfer process. This is due to experimental challenges in separating direct from indirect transfer as both processes o…
Heavy-Ion Microbeam Studies of Single-Event Leakage Current Mechanism in SiC VD-MOSFETs
2020
Heavy-ion microbeams are employed for probing the radiation-sensitive regions in commercial silicon carbide (SiC) vertical double-diffused power (VD)-MOSFETs with micrometer accuracy. By scanning the beam spot over the die, a spatial periodicity was observed in the leakage current degradation, reflecting the striped structure of the power MOSFET investigated. Two different mechanisms were observed for degradation. At low drain bias (gate and source grounded), only the gate-oxide (at the JFET or neck region) is contributing in the ion-induced leakage current. For exposures at drain–source bias voltages higher than a specific threshold, additional higher drain leakage current is observed in t…
Impact of Terrestrial Neutrons on the Reliability of SiC VD-MOSFET Technologies
2021
Accelerated terrestrial neutron irradiations were performed on different commercial SiC power MOSFETs with planar, trench and double-trench architectures. The results were used to calculate the failure cross-sections and the failure in time (FIT) rates at sea level. Enhanced gate and drain leakage were observed in some devices which did not exhibit a destructive failure during the exposure. In particular, a different mechanism was observed for planar and trench gate MOSFETs, the first showing a partial gate rupture with a leakage path mostly between drain and gate, similar to what was previously observed with heavy-ions, while the second exhibiting a complete gate rupture. The observed fail…
Isotopic Enriched and Natural SiC Junction Barrier Schottky Diodes Under Heavy Ion Irradiation
2022
The radiation tolerance of isotopic enriched and natural silicon carbide junction barrier Schottky diodes are compared under heavy ion irradiation. Both types of devices experience leakage current degradation as well as single-event burnout events. The results were comparable, although the data may indicate a marginally lower thresholds for the isotopic enriched devices at lower linear energy transfer (LET). Slightly higher reverse bias threshold values for leakage current degradation were also observed compared to previously published work.