Silicon carbide (SiC) n-channel and p-channel junction field-effect transistors (JFETs) were fabricated by direct ion implantation into a high-purity semi-insulating 4H-SiC substrate toward ...complementary-JFET integrated circuit applications under a harsh environment. The fabricated n-JFET and p-JFET on a common substrate without an epitaxial layer show normal transistor operations up to 400 °C. Their electrical characteristics are comparable with theoretical estimations obtained from material parameters of n- and p-type SiC epitaxial layers. The present results assure that not only JFETs but also a variety of devices can be made by direct ion implantation while keeping material properties of epitaxially grown SiC.
Ultrahigh-voltage SiC flip-type n-channel implantation and epitaxial (IE)-IGBTs were developed, and the static and dynamic performance was investigated. A large device (8 mm × 8mm) with a blocking ...voltage greater than 16 kV was achieved, and an on-state current of 20 A was obtained at the low on-state voltage (Von) of 4.8 V. RonAdiff was 23 mΩ·cm2 at Von = 4.8 V. In order to evaluate the switching characteristics of the IE-IGBT, ultrahigh-voltage power modules were assembled. A chopper circuit configuration was used to evaluate the switching characteristics of the IE-IGBT. Smooth turn-off waveforms were successfully obtained at VCE = 6.5 kV and ICE = 60 A in the temperature range from room temperature to 250°C.
Impact of step height of silicon carbide (SiC) substrates on heteroepitaxial growth of aluminum nitride (AlN) was investigated. Step-and-terrace structures with various step heights, 6 monolayer ...(ML), 3ML and 1ML, were formed on 6H–SiC (0
0
0
1) vicinal substrates by high-temperature gas etching. 2H–AlN layers were grown on the substrate by plasma-assisted molecular-beam epitaxy (MBE) and then these layers were characterized by atomic-force microscopy (AFM) and X-ray diffraction (XRD). High-quality AlN can be grown on SiC substrates with 6ML- and 3ML-height step, while AlN grown on SiC substrates with 1ML-height step exhibited inferior crystalline quality. A model for high-quality AlN growth on SiC substrates with 3ML-height step is proposed.
Phonon frequencies of a high-quality AlN layer coherently grown on a 6H-SiC (0001) substrate are investigated by Raman scattering. Owing to the largest strain in our coherent AlN layer among ...heteroepitaxially grown AlN layers ever reported, phonon frequencies of the E2 (low), E2 (high), and A1 (LO) modes are considerably shifted to 244.5 (−3.3, compared with bulk AlN), 672.1 (+16.3), and 899 (
+
11
)
cm
−
1
, respectively. Full widths at half maximum of the phonon modes in the coherent AlN are almost equal to those of high-quality bulk AlN, clearly indicating its high crystalline quality and uniform strain. We discuss accuracy of phonon deformation potentials reported by several other groups thorough comparing our experimental results.
A lateral trench SiC MOSFET with lateral conduction on the side walls was designed using an ultra-narrowbody (UNB) sandwiched by the trench walls. The p-body is designed to be very narrow in order to ...avoid any depletion region formed in its body. The structure is similar to a FinFET, but applied to a SiC device. The body width in the channel region of the fabricated UNB MOSFET was 55 nm. The drain current of the UNB and conventional MOSFET were 1.27 μA and 0. 11μA, respectively, at V_{D S}=30 V. The UNB structure presented a significant increase in the mobility, reaching values of over 200cm 2 /Vs. The result indicated a very prominent FinFET effect, resulting in very high mobility and hence very significant improvement in the channel resistance of SiC MOSFETs.
We report on the electrical characterization, by means of deep level transient spectroscopy, of electron-irradiated Al-doped 6H-SiC epilayers. Samples were irradiated with either 116 keV, in order to ...displace only carbon atoms, or 400 keV. Seven deep traps, in the 0.1-1.6 eV range above the valence band, were found. The thermal stability of the detected levels was analyzed by performing an isochronal annealing series in the 100-1800 °C temperature range and the atomic structure of most of the detected traps was found to be related to C-displacement.
A dramatic improvement of inversion channel mobility in 4H-SiC MOSFETs was successfully achieved by utilizing the (112~0) face: 17 times higher (95.9 cm 2 /Vs) than that on the conventional (0001) ...Si-face (5.59 cm 2 /Vs). A low threshold voltage of MOSFETs on the (112~0) face indicates that the (112~0) MOS interface has fewer negative charges than the (0001) MOS interface. Small anisotropy of channel mobility in 4H-SiC MOSFETs (μ/sub (11~00)//μ/sub (0001)/=0.85) reflects the small anisotropy in bulk electron mobility.
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