Papers by Author: Gan Feng

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Authors: Tsunenobu Kimoto, Gan Feng, Toru Hiyoshi, Koutarou Kawahara, Masato Noborio, Jun Suda
Abstract: Extended defects and deep levels generated during epitaxial growth of 4H-SiC and device processing have been reviewed. Three types in-grown stacking faults, (6,2), (5,3), and (4,4) structures, have been identified in epilayers with a density of 1-10 cm-2. Almost all the major deep levels present in as-grown epilayers have been eliminated (< 1x1011 cm-3) by two-step annealing, thermal oxidation at 1150-1300oC followed by Ar annealing at 1550oC. The proposed two-step annealing is also effective in reducing various deep levels generated by ion implantation and dry etching. The interface properties and MOSFET characteristics with several gate oxides are presented. By utilizing the deposited SiO2 annealed in N2O at 1300oC, a lowest interface state density and a reasonably high channel mobility for both n- and p-channel MOSFETs with an improved oxide reliability have been attained.
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Authors: Hiroki Niwa, Gan Feng, Jun Suda, Tsunenobu Kimoto
Abstract: Breakdown characteristics of 4H-SiC PiN diodes with various JTE structures have been investigated. By combining two-zone JTE and Space-Modulated JTE (SM-JTE), a breakdown voltage over 15 kV, corresponding to about 93 % of the parallel-plane breakdown voltage, was realized. The window of optimum JTE dose to obtain high breakdown voltage was widened, which indicates the robustness to the deviation of JTE dose. By comparing the breakdown voltage obtained by simulation and experimental results, impacts of the charge near the SiO2/SiC interface are discussed.
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Authors: Gan Feng, Jun Suda, Tsunenobu Kimoto
Abstract: Dislocations in 4H-SiC epilayers were imaged nondestructively by means of micro photoluminescence (-PL) mapping at room temperature. The one-to-one correspondence between the individual dislocations and the -PL mapping contrast has been consistently obtained. By analyzing the reduction of the intensity in the -PL mapping image performed at 390 nm (near band-edge emission), we were able to distinguish threading screw dislocations and threading edge dislocations. Furthermore, the contrast of dislocations in PL-intensity mapping image greatly depends on the carrier lifetimes of the 4H-SiC epilayers. Lifetimes longer than 0.5 s are essential to obtain a discernible contrast for the individual dislocations.
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Authors: Gan Feng, Jun Suda, Tsunenobu Kimoto
Abstract: In-grown stacking faults (IGSFs) in thick 4H-SiC epilayers grown at high growth rates have been characterized by micro-photoluminescence (micro-PL) spectroscopy and its intensity mapping. Strong PL emissions from the IGSFs are observed even at room temperature. Three kinds of IGSFs have been identified in the samples based on the micro-PL spectra. Each IGSF shows the specific PL emission peak located at 460 nm, 480 nm, and 500 nm, respectively. The shapes, distributions, and densities of IGSFs in the epilayers are revealed by the micro-PL intensity mapping. The stacking sequences of three IGSFs have been determined as (4,4), (3,5), and (6,2) in the Zhadonov’s notation, respectively, by high-resolution transmission electron microscopy observations. Three identified IGSFs are then classified as quadruple Shockley SFs, triple Shockley SFs, and double Shockley SFs, respectively, based on the shear formation model.
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Authors: Gan Feng, Jun Suda, Tsunenobu Kimoto
Abstract: The micro-photoluminescence (micro-PL) spectroscopy and its intensity mapping have been utilized to investigate the planar defects, stacking faults (SFs), in 4H-SiC epilayers. Strong PL emissions from the SFs are observed even at room temperature. It is found that each kind of SF shows the distinct PL emission behaviours. Three kinds of SFs: intrinsic Frank SFs, double Shockley SFs, and in-grown SFs, have been identified in the samples based on the micro-PL spectra. At the same time, the micro-PL intensity mapping at the emission band of each SF has been performed to spatially profile the SFs. The shapes, distributions, and densities of SFs in the epilayers are then presented. The PL emission behaviours of each SF at low temperature are also studied.
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