1950°C annealing of Al+ implanted 4H-SiC: Sheet resistance dependence on the annealing time
TL;DR: In this paper, after annealing at 1950°C, a 1×1020 cm-3 Al+ implanted 4H-SiC material shows a decreasing resistivity with increasing annaling time in the range 5-25 min.
Abstract: This study shows that, after annealing at 1950°C, a 1×1020 cm-3 Al+ implanted 4H-SiC material shows a decreasing resistivity with increasing annealing time in the range 5-25 min. After this, the resistivity remains constant up to an annealing time of 40 min. The estimated minimum time to gain the thermal equilibrium in this implanted material at 1950°C is 12 min. Electrical characterization has been performed in the 20-680 K temperature range.
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TL;DR: In this article, a 4H-SiC trench insulated gate bipolar transistor (IGBT) incorporating a Schottky contact in the collector side is proposed to reduce the turn-off energy loss.
Abstract: In this paper, a 4H-SiC trench insulated gate bipolar transistor (IGBT) incorporating a Schottky contact in the collector side is proposed to reduce the turn-off energy loss. The proposed structure is explored and compared with the conventional IGBT using ATLAS. The simulation results have indicated that the reduction in turn-off energy loss is more than 88%, with a slight degradation in the ${I}$ – ${V}$ characteristics. Concurrently, with the same on-state voltage drop, the turn-off loss is reduced by a figure of 84%.
12 citations
TL;DR: In this article, the authors confirm and extend the results of a previous study where a variable range hopping transport through localized impurity states has been found to dominate the electrical transport properties of 3×1020 cm-3 and 5× 1020 cm 3 Al+ implanted 4H-SiC layers after 1950-2000 °C post implantation annealing.
Abstract: In this work, we confirm and extend the results of a previous study where a variable range hopping transport through localized impurity states has been found to dominate the electrical transport properties of 3×1020 cm-3 and 5×1020 cm-3 Al+ implanted 4H-SiC layers after 1950-2000 °C post implantation annealing. In this study, samples with longer annealing times have been taken into account. The temperature dependence of these sample conductivity follows a variable range hopping law, consistent with a nearly two-dimensional hopping transport of non-interacting carriers that in the highest doped samples, persists up to around room temperature. This result indicates that the hole transport becomes strongly anisotropic on increasing the doping level. At the origin of this unusual electrical behavior, may be the presence of basal plane stacking faults, actually observed by transmission electron microscopy in one of the 5×1020 cm-3 samples
5 citations
Cites result from "1950°C annealing of Al+ implanted 4..."
...In fact, the lower values of and Ropt obtained for the sample SIC0293g, submitted to a longer annealing time with respect to sample SIC0293e, suggest that (i) the amount of disorder can evolve during the thermal treatment without affecting d, and (ii) ( ) may increases with time, as a result of a more efficient activation of the implanted impurities, in agreement with the results of [9]....
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References
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TL;DR: In this article, the dependences of the electrical properties on the implanted Al+ dose and on the annealing time were examined by Hall effect measurements, and the experimentally obtained free-hole concentrations agree well with the theoretically expected values.
Abstract: High-dose aluminum-ion (Al+) implantation into 4H-SiC (0001) and (112¯0) has been investigated. The dependences of the electrical properties on the implanted Al+ dose and on the annealing time were examined by Hall-effect measurements. A low sheet resistance of 2.3kΩ∕◻ (0.2μm deep) was obtained in a (0001) sample by implantation of Al+ with a dose of 3.0×1016cm−2 at 500°C and a subsequent high-temperature anneal at 1800°C for a short time of 1min. In the case of (112¯0) samples, even room-temperature implantation resulted in a low sheet resistance of 2.3kΩ∕◻ (0.2μm-deep) after anneal at 1800°C. The Hall data are compared with the calculated values determined by using the doping-concentration dependent ionization energy of Al acceptors. The experimentally obtained free-hole concentrations agree well with the theoretically expected values. Hole mobilities are not as high as the empirical mobilities obtained in Al-doped epitaxial layers. The differences in the electrical properties between the experimental d...
75 citations
"1950°C annealing of Al+ implanted 4..." refers background or methods in this paper
...3 is absolutely different from that shown in [1]....
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...in [1], or the value of the annealing temperature, 1950°C in this study and 1800°C in [1], or both....
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...In [1], where the Al implanted concentration was 3×10 21 cm -3 and post implantation annealing was performed with carbon cap (C-cap), simultaneously the sheet resistance increased and the free hole density decreased for increasing annealing time in the range 1-200 min....
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...The academic research has pushed the post implantation annealing temperature of Al + implanted 4H-SiC at and above 1800°C in order to improve the electrical activation of the implanted Al [1-3]....
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...To the best of the authors knowledge, at such high temperatures systematic studies on the effect of the annealing time have been performed only at 1800°C annealing temperature [1,4] and for Al concentration values not always declared....
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TL;DR: In this paper, a pyrolyzed photoresist film called carbon-cap (C-cap) is used as a protective cap of the surface of ion-implanted 4H-SiC wafers during the postimplantation annealing process with the aim to prevent Si sublimation and step bunching formation.
Abstract: A pyrolyzed photoresist film is commonly used as a protective cap of the surface of ion-implanted 4H-SiC wafers during the postimplantation annealing process with the aim to prevent Si sublimation and step bunching formation. Such a film that is called carbon-cap (C-cap) is always removed after postimplantation annealing and before any other processing step of the SiC wafer. Here, we show that this C-cap is a continuous, hard, black, mirrorlike, and planar thin film that can be patterned by a reactive ion etching O 2 -based plasma for the fabrication of ohmic contact pads on both Al + - and P + -implanted 4H-SiC. This C-cap material has an electrical resistivity of 1.5 × 10 -3 Ω cm and a good resistance against scratch. Al (1% Si) wires can be ultrasonically bonded on the C-cap pads. Such a bonding and the C-cap adhesion to the implanted 4H-SiC surface are stable for electrical characterizations in vacuum between room temperature and 450°C. The measured specific contact resistance of the C-cap on a 1 × 10 20 cm -3 p+-implanted 4H-SiC is 9 × 10- 5 Ω cm 2 at room temperature. Micro-Raman characterizations show that this C-cap is formed of a nanocrystalline graphitic phase.
55 citations
"1950°C annealing of Al+ implanted 4..." refers methods in this paper
...After implantation the wafer has been cut in 5 mm × 5 mm samples, the SiO2 film has been removed by wet etching, and the implanted face of every specimen has been protected by spinning a resist film subsequently pyrolyzed (C-cap) in forming gas [5]....
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TL;DR: In this paper, the donor-acceptor pair luminescence due to P-Al pairs in 4H-SiC was investigated and the ionization energy of the deeper donor at the cubic site was determined, 125.5meV.
Abstract: This paper deals with fitting the donor-acceptor pair luminescence due to P-Al pairs in 4H-SiC. It was possible to identify P at the Si cubic site as the shallower donor with ionization energy of 60.7meV, as well as to distinguish the contribution in the spectrum from pairs involving this donor and Al acceptors from both the cubic and hexagonal lattice sites, leading to justification of their ionization energies. The case of N-Al pair luminescence was revisited and the ionization energy of the deeper Nc donor at the cubic site was determined, 125.5meV. © 2005 The American Physical Society.
51 citations
"1950°C annealing of Al+ implanted 4..." refers background in this paper
...(a) energy of diluted dopant Al in 4H-SiC [7]....
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TL;DR: In this article, the p-type doping of high purity semi-insulating 4H polytype silicon carbide (HPSI 4H-SiC) by aluminum ion (Al+) implantation has been studied in the range of 1 × 1019 to 8 × 1020 /cm3 and a conventional thermal annealing of 1950 °C/5 min.
Abstract: The p-type doping of high purity semi-insulating 4H polytype silicon carbide (HPSI 4H-SiC) by aluminum ion (Al+) implantation has been studied in the range of 1 × 1019 to 8 × 1020 /cm3 (0.39 μm implanted thickness) and a conventional thermal annealing of 1950 °C/5 min. Implanted 4H-SiC layers of p-type conductivity and sheet resistance in the range of 1.6 × 104 to 8.9 ×102 Ω□, corresponding to a resistivity in the range of 4.7 × 10−1 to 2.7 × 10−2 Ω cm have been obtained. Hall carrier density and mobility data in the temperature range of 140–720 K feature the transition from a valence band to an intraband conduction for increasing implanted Al ion concentration from 1 × 1019 /cm3 to 4 × 1020 /cm3. A 73% electrical activation, 31% compensation and 146 meV ionization level have been obtained using a best-fit solution of the neutrality equation to Hall carrier data for the lowest concentration.
44 citations
"1950°C annealing of Al+ implanted 4..." refers methods in this paper
...The academic research has pushed the post implantation annealing temperature of Al + implanted 4H-SiC at and above 1800°C in order to improve the electrical activation of the implanted Al [1-3]....
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TL;DR: In this paper, a microwave heating technique has been used for the electrical activation of Al+ ions implanted in semi-insulating 4H-SiC. Annealing temperatures in the range of 2000-2100 °C and annealing time of 30 s have been used.
Abstract: A microwave heating technique has been used for the electrical activation of Al+ ions implanted in semi-insulating 4H-SiC. Annealing temperatures in the range of 2000–2100 °C and annealing time of 30 s have been used. The implanted Al concentration has been varied from 5×1019 to 8×1020 cm-3. A minimum resistivity of 2×10-2 Ωcm and about 70% electrical activation of the implanted Al have been measured at room temperature for an implanted Al concentration of 8×1020 cm-3 and microwave annealing at 2100 °C for 30 s.
35 citations