Papers by Keyword: Al Doping

Abstract: In the range 80 K-900 K, we have investigated the electrical properties of heavily aluminum in-situ doped, 4H-SiC samples. The temperature dependence of the hole concentration and Hall mobility was analyzed in the model taking into account heavy and light holes. The modelisation parameters were compared with experimental values of Secondary Ion Mass Spectroscopy (SIMS) and Capacitance-Voltage (CV) measurements.

Abstract: Low resistivity p-type SiC bulk crystals were grown by the sublimation method with using aluminum and nitrogen co-doping. In the sublimation growth of 4H-SiC, to obtain low-resistive p-type crystals are not easy because of the instability of 4H-SiC polytype with highly Al-doping. We have grown < 90 mΩcm p-type 4H-SiC bulk crystals with the co-doping condition. The results of SIMS and Raman spectroscopy show that high concentration of nitrogen co-doping could be effective to the stabilization of 4H polytype with p-type SiC growth.

Abstract: Al doping of 4H-SiC with high surface concentration and deep depth profile is found to be realized by irradiating single-pulse excimer laser to an Al film deposited on the surface. Optical emission spectra suggest that high-temperature molten Al is produced behind the laser-generated high-density Al plasma and Al is diffused from the molten Al into 4H-SiC. The Al doping depth reaches to ~200 nm by irradiating a single laser pulse. A pn junction diode fabricated by the doping with the molten Al shows on/off ratio over 10 orders of magnitude.

Abstract: P/N junctions have been fabricated with N⁺ commercial 4H-SiC substrate on which Vapor-Liquid-Solid (VLS) selective epitaxy was used to create a localized p-type doping. The influence of the carrier gas nature (argon or hydrogen) has been investigated in terms of quality of the growth morphology, deposit thickness and electrical behavior of the P/N junction. Distinct results have been observed with a clear improvement when using VLS selective epitaxy under hydrogen.

Abstract: 4H-SiC junction photodiodes, obtained by aluminium (Al) ion- implantation on low doped n-type epilayers are widely characterized observing an extremely low dark current density < 1 nA/cm2 at -100 V up to 90°C, a peak responsivity of 0.11 A/W at 280 nm corresponding to a quantum efficiency of 50% and a visible blindness > 10³. The absence of optically active defects and pairs recombination centers was monitored by electro-optical and Emission Microscopy measurements.

Abstract: This work describes the growth of 1-D Al-doped ZnO nanorods via low temperature hydrothermal reaction on seeded substrates. The amount of Al doped ZnO nanorods were tuned by using different concentration of aluminum nitrate from 1-20 mM. The optimum 5 mM Al doping produced an arrays of sharp-tip nanorods with average length of ~1.16 μm and average diameter of ~118 nm. I-V characteristic of the Al-doped ZnO nanorods fabricated onto Al electrodes were observed under UV illumination and dark condition. The change in photoconductivity of Al-doped ZnO nanorods under UV light was found two orders of times higher compared to ZnO nanorods. Different concentrations of aluminium doped ZnO nanorods UV sensing showed response to UV light but with different sensing value. 5 mM Al-doped ZnO showed high responsivity of fabricated UV sensing at 3V with 23.56 A/W which was higher compared to other concentrations. This suggested that the responsivity of Al-doped ZnO NRs UV sensing could be controlled to some extent by controlling the percentage of Al-doped.

Abstract: In this paper, Al(NO3)3•9H2O was used as raw material and the nanoparticles of Al-doped TiO2 were prepared by hydrothermal method. The nanoparticles and films were characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM), Ultraviolet and Visible Spectroscopy (UV-Vis). The flat band potential (Efb) of nanostructured TiO2 and Al-doped TiO2 in acetone have been determined with spectroelectrochemistry measurement. The results show that Al doping decreases the energy gap and improves the absorption ability in visible region. On the other hand, Al doping TiO2 can effectively embarrass the crystal growth of TiO2. Specifically, the Efb of TiO2 and Al-doped TiO2 can be determined to be -0.6 V and -0.3V.

Abstract: LiAl0.1Mn1.9O4 materials were prepared by a solution combustion synthesis method. In order to improve the purity of the products, the effect of further calcination time was investigated. The phase compositions of the as-prepared products were determined by X-ray diffraction (XRD). The electrochemical performance of the products was tested by using a coin-type half battery versus lithium metal foil as anode material. XRD results suggested that the main phase of the products was LiAl0.1Mn1.9O4, and there was a trace amount Mn2O3 impurity in some of the products. The purity, crystallinity and grain size of the LiAl0.1Mn1.9O4 were increased with increasing further calcination time. Electrochemical experiments demonstrate that the initial discharge capacities of the products with further calcination time of 0, 6, 12 and 24h were 93.7, 105.7, 114.0 and 120.6mAh/g, and about 89.8, 89.5, 89.2 and 88.3% of the initial capacities were retained after 25 cycles, respectively. Further calcination time can enhance the initial capacity, but is not favorable for the cycle ability of the products.

Abstract: Focusing on the change in aluminium-related photoluminescence lines in 4H-SiC versus doping concentration, we have used a combination of LTPL (Low Temperature PhotoLuminescence) and secondary ion mass spectrometry measurements to set new calibration curves. In this way, one can probe the change in aluminum concentration in the range 10¹⁷ to 10¹⁹ cm^-3. When applied to LTPL maps collected on full 3-inch wafers, we show that such abacuses constitute a powerful tool to control efficiently the doping level of as-grown p⁺ (emitters) and p⁺⁺ (contact) layers for power device applications.

Abstract: We report on n-type 3C-SiC samples grown by sublimation epitaxy. We focus on the low temperature photoluminescence intensity and show that the presence of a first conversion layer, grown at low temperature, is not only beneficial to improve the homogeneity of the polytype conversion but, also, to the LTPL signal intensity. From the use of a simple model, we show that this comes from a reduced density of non-radiative recombination centers.