Papers by Keyword: Corona

Abstract: A breakthrough high throughput WBG semiconductor dopant monitoring method has recently been introduced based on the novel concept of sweeping the electrical bias by near UV illumination-induced photoneutralization of corona charge. As originally discovered for 4H-SiC, the doping determination can be realized using the value of the photoneutralization time constant. In the present work this procedure is tested for β-Ga₂O₃ with a larger energy gap of 4.8eV, using a correspondingly deeper UV range. Such deep UV application to the AlGaN/GaN HEMT structure resulted in the development of a new measurement principle capable of increasing the HEMT wafer measurement throughput 10 times compared to previous corona noncontact C-V metrology. The new principle involves a linear illumination-induced corona charge bias sweep. Combined with surface voltage monitoring, it provides a means for fast and precise determination of the pinch-off voltage, V_P, the AlGaN electrical thickness, and the 2D electron gas density.

Abstract: We discuss two defect related practical improvements in the corona noncontact CV metrology, (CnCV) for SiC. The improvements are introduced in response to requests from industrial tool users. The first improvement quantifies mapping of electrically active defects with the QUAD technique (Quality, Uniformity, and Defects). It provides the capability of user selectable die grids directly comparable with Near UV-PL and optical defect mapping. This shall enhance understanding of the device killer defects and help to correlate epilayer defects and device yield. The second improvement introduces auto-remeasurement of outliers appearing in doping measurements on defective sites. This procedure is analogous to that used in the Hg probe technique and it provides a means for correcting defect related distortions in SPC doping monitoring charts.

Abstract: Wide bandgap semiconductor technology has been generating a great deal of attention due to its fundamental advantages in high power electronics. Understanding and effective control of interfacial properties belong to a group of critical issues requiring progress. In this work, we report progress in wide bandgap interface characterization, achieved using photo-ionization of deep traps under a non-equilibrium condition created by corona-charge bias in deep depletion. This characterization capability is demonstrated on oxidized n-type epitaxial SiC with deep interfacial traps invisible in standard C-V. These traps, initially present at high density, are shown to be reduced by half after a wet anneal. The photo-ionization technique is incorporated in commercially available non-contact C-V (CnCV) metrology [1,2] providing a non-invasive, cost and time saving metrology that benefits development research as well as device fabrication.

Abstract: We report significant advancements in corona-based non-contact capacitance-voltage (CnCV) metrology recently developed for comprehensive C-V characterization of SiC and other wide bandgap semiconductors. The technique answers the industries needs for nondestructive, cost-effective C-V dopant monitoring for material and device development and manufacturing control. Excellent precision and matching to mercury probe CV is demonstrated for SiC, Ga₂O₃, GaN and AlGaN/GaN structures over a concentration range from 10¹⁴cm^-3 to 2x10¹⁹cm^-3. The emphasis in the present work is on improvement of CnCV in dopant depth profiling resolution and measurement throughout. This is achieved with a variable charge method that in-situ adjusts corona charging increments in response to changes in dopant concentration. Results are presented for multi-layer epitaxial SiC and for 2DEG in AlGaN/GaN HEMT structures. The latter represents an extreme case of high-low concentration profiling with a transition from 10²⁰electrons/cm^-3 in the 2D electron gas to a fully depleted well and dopant concentration in the 10¹⁵cm^-3 range.

Abstract: Gallium oxide was grown on silicon carbide substrates using a corona discharge assisted vapor phase epitaxy process and gold catalyst. It is shown that by implementing the corona discharge the morphology of the gallium oxide can be transformed. The excitation of the gas phase and the generation of excited species directly influence the growth morphology suppressing nanowire growth and supporting the transformation into heteroepitaxial growth.

Abstract: In this work we present novel photo-assisted characterization of dielectric interfaces in SiC using a modified non-contact corona-Kelvin technique. This technique eliminates the cost and time associated with fabrication of electrical test structures. UV illumination in deep depletion is used to generate minority carriers that empty deep interface states too slow to be emptied by thermal emission. After illumination, the interface state charging current is measured with time resolved voltage decay. This enables novel non-contact corona-Kelvin characterization of hole emission and electron capture processes involving slow interface states. This novel application complements standard corona-Kelvin measurement of dielectric, interface and semiconductor parameters.

Abstract: Gallium oxide nanowires were grown on different substrates using a corona plasma assisted vapor phase epitaxy process and gold catalyst. It is shown that the silicon carbide pseudo substrate in combination with the plasma excitation of the gas phase supports the growth of the gallium oxide nanowires. Analyzing the orientation of the nanowires with respect to the growth surface, it is concluded that the nanowires growth proceed along the fast growth direction of gallium oxide.

Abstract: TGZ10A-40.5 wall bushing of high voltage switch cabinet from one company was taken as applied research object. Reference the development process of high voltage cable shielding technology, three samples were designed and produced depending on different sets of the shield system. The result show that: surfaces processed by the way that the inner (aluminum cylinder) and the outer (metal mesh ring) shielding components were coated with a semi-conductive material, made little sense to improve the withstand voltage level and reduce the partial discharge; surface processed by the way that inner shield component (aluminum cylinder) was coated with semi-conductive material, the outer shield component (metal mesh ring) was not coated with semi-conductive material, was obviously influenced the improvement of the withstand voltage level and reduction of the partial discharge, compared with traditional technology, the average start voltage of corona increased 23.8%, the average value of partial discharge dropped 27.7%.

Abstract: At high altitudes, 330 kV dampers usually have corona discharges on their weights, which affects the lives of the surrounding residents. To suppress the corona, optimizing the structures of the dampers is a recommended measure to reduce the electric field intensities on their weights. In this paper, three-dimensional computational models of 330 kV FDN dampers were constructed to calculate the electric field distributions on their weights, based on finite element method (FEM). The structure of the small end was optimized to reduce the electric field strength on its surface. When the radius was increased from 25 to 35 mm, the maximum electric field intensity could be decreased from 2987 V/mm to 2390V/mm. According to the results, new dampers were manufactured to test their corona characteristics. The test results show that the new dampers can prevent corona discharge at altitudes below 3500 m.

Abstract: The HTV SIR provided the superior hydrophobicity for the composite insulator. But it faces the aging problem more than the inorganics. Corona, as an inevitable influence factor in insulator’s operation, its effect to the material could not be ignored. The paper developed a multi needles to plate corona aging equipment, 1000 hours’ corona aging to the HTV SIR was done. The duration of corona aging effect was study by FTIR, SEM and volume resistivity-temperature character testing. Three testing methods from the aspect of material’s chemical, physical and electrical characters to evaluate the aging effect with time went on. It had good consistency in all three methods for HTV SIR’s corona aging evaluation.