| 1. |
- Khosa, Rabia Y., et al.
(författare)
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Electrical characterization of amorphous Al2O3 dielectric films on n-type 4H-SiC
- 2018
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Ingår i: AIP Advances. - : AIP Publishing. - 2158-3226 .- 2158-3226. ; 8:2
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Tidskriftsartikel (refereegranskat)abstract
- We report on the electrical properties of Al 2 O 3 films grown on 4H-SiC by successive thermal oxidation of thin Al layers at low temperatures (200°C - 300°C). MOS capacitors made using these films contain lower density of interface traps, are more immune to electron injection and exhibit higher breakdown field (5MV/cm) than Al 2 O 3 films grown by atomic layer deposition (ALD) or rapid thermal processing (RTP). Furthermore, the interface state density is significantly lower than in MOS capacitors with nitrided thermal silicon dioxide, grown in N 2 O, serving as the gate dielectric. Deposition of an additional SiO 2 film on the top of the Al 2 O 3 layer increases the breakdown voltage of the MOS capacitors while maintaining low density of interface traps. We examine the origin of negative charges frequently encountered in Al 2 O 3 films grown on SiC and find that these charges consist of trapped electrons which can be released from the Al 2 O 3 layer by depletion bias stress and ultraviolet light exposure. This electron trapping needs to be reduced if Al 2 O 3 is to be used as a gate dielectric in SiC MOS technology.
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| 2. |
- Khosa, Rabia Y., et al.
(författare)
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Electrical characterization of high k-dielectrics for 4H-SiC MIS devices
- 2019
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Ingår i: Materials Science in Semiconductor Processing. - : Elsevier BV. - 1369-8001 .- 1873-4081. ; 98, s. 55-58
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Tidskriftsartikel (refereegranskat)abstract
- We report promising results regarding the possible use of AlN or Al 2 O 3 as a gate dielectric in 4H-SiC MISFETs. The crystalline AlN films are grown by hot wall metal organic chemical vapor deposition (MOCVD) at 1100 °C. The amorphous Al 2 O 3 films are grown by repeated deposition and subsequent low temperature (200 °C) oxidation of thin Al layers using a hot plate. Our investigation shows a very low density of interface traps at the AlN/4H-SiC and the Al 2 O 3 /4H-SiC interface estimated from capacitance-voltage (CV) analysis of MIS capacitors. Current-voltage (IV) analysis shows that the breakdown electric field across the AlN or Al 2 O 3 is ∼ 3 MV/cm or ∼ 5 MV/cm respectively. By depositing an additional SiO 2 layer by plasma enhanced chemical vapor deposition at 300 °C on top of the AlN or Al 2 O 3 layers, it is possible to increase the breakdown voltage of the MIS capacitors significantly without having pronounced impact on the quality of the AlN/SiC or Al 2 O 3 /SiC interfaces.
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| 3. |
- Khosa, Rabia Y., et al.
(författare)
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Electrical characterization of MOCVD grown single crystalline ALN thin films on 4H-SiC
- 2019
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Ingår i: Materials Science Forum. - : Trans Tech Publications Ltd. - 1662-9752 .- 0255-5476. ; 963 MSF, s. 460-464, s. 460-464
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Konferensbidrag (refereegranskat)abstract
- We report on a very low density of interface traps at the AlN/4H-SiC interface estimated from capacitance-voltage (CV) analysis of metal-insulator-semiconductor (MIS) capacitors. Single crystalline aluminum nitride (AlN) films are grown by metal organic chemical vapor deposition (MOCVD). Current-voltage (IV) analysis shows that the breakdown electric field across the AlN dielectric is 3 MV/cm. By depositing an additional SiO2 layer on top of the AlN layer it is possible to increase the breakdown voltage of the MIS capacitors significantly without having pronounced impact on the quality of the AlN/SiC interface.
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| 4. |
- Khosa, Rabia Y., et al.
(författare)
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Electrical properties of 4H-SiC MIS capacitors with AlN gate dielectric grown by MOCVD
- 2019
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Ingår i: Solid-State Electronics. - : Elsevier BV. - 0038-1101 .- 1879-2405. ; 153, s. 52-58
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Tidskriftsartikel (refereegranskat)abstract
- We report on the electrical properties of the AlN/4H-SiC interface using capacitance- and conductance-voltage (CV and GV) analysis of AlN/SiC MIS capacitors. The crystalline AlN layers are made by hot wall MOCVD. CV analysis at room temperature reveals an order of magnitude lower density of interface traps at the AlN/SiC interface than at nitrided SiO2/SiC interfaces. Electron trapping in bulk traps within the AlN is significant when the MIS capacitors are biased into accumulation resulting in a large flatband voltage shift towards higher gate voltage. This process is reversible and the electrons are fully released from the AlN layer if depletion bias is applied at elevated temperatures. Current-voltage (IV) analysis reveals that the breakdown electric field intensity across the AlN dielectric is 3–4 MV/cm and is limited by trap assisted leakage. By depositing an additional SiO2 layer on top of the AlN layer, it is possible to increase the breakdown voltage of the MIS capacitors significantly without having much impact on the quality of the AlN/SiC interface.
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