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Influence of GaN- and Si?N?-Passivation Layers on the Performance of AlGaN/GaN Diodes With a Gated Edge Termination
摘要： This paper analyses the influence of the GaN and Si3N4 passivation (or 'cap') layer on the top of the AlGaN barrier layer on the performance and reliability of Schottky barrier diodes with a gated edge termination (GET-SBDs). Both GaN cap and Si3N4 cap devices show similar dc characteristics but a higher density of traps at the SiO2/GaN interface or/and an increase of the total dielectric constant in the access region result in higher RON-dispersion in GaN cap devices. The leakage current at medium/low temperatures in both types of devices shows two low-voltage-independent activation energies, suggesting thermionic and field-emission processes to be responsible for the conduction. Furthermore, a voltage-dependent activation energy in the high-temperature range occurs from low voltages in the GaN cap devices and limits their breakdown voltage (VBD). Time-dependent dielectric breakdown measurements show a tighter distribution in Si3N4 cap devices (Weibull slope β = 3.3) compared to GaN cap devices (β = 1.8). Additional measurements in plasma-enhanced atomic layer deposition (PEALD)-Si3N4 capacitors with different cap layers and TCAD simulations show an electric field distribution with a strong peak within the PEALD-Si3N4 dielectric at the GET corner, which could accelerate the formation of a percolation path and provoke the device breakdown in GaN cap SBDs even at low-stress voltages.
关键词： Si3N4 cap,GaN cap,AlGaN/GaN Schottky diode,reliability,breakdown voltage,passivation layer,off-state,Activation energy
更新于2025-09-23 15:23:52
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Current linearity and operation stability in Al <sub/>2</sub> O <sub/>3</sub> -gate AlGaN/GaN MOS high electron mobility transistors
摘要： To investigate current linearity and operation stability of metal–oxide–semiconductor (MOS) AlGaN/GaN high electron mobility transistors (HEMTs), we have fabricated and characterized the Al2O3-gate MOS-HEMTs without and with a bias annealing in air at 300 °C. Compared with the as-fabricated (unannealed) MOS HEMTs, the bias-annealed devices showed improved linearity of ID–VG curves even in the forward bias regime, resulting in increased maximum drain current. Lower subthreshold slope was also observed after bias annealing. From the precise capacitance–voltage analysis on a MOS diode fabricated on the AlGaN/GaN heterostructure, it was found that the bias annealing effectively reduced the state density at the Al2O3/AlGaN interface. This led to efficient modulation of the AlGaN surface potential close to the conduction band edge, resulting in good gate control of two-dimensional electron gas density even at forward bias. In addition, the bias-annealed MOS HEMT showed small threshold voltage shift after applying forward bias stress and stable operation even at high temperatures.
关键词： current linearity,interface states,MOS-HEMT,AlGaN/GaN,operation stability,bias annealing
更新于2025-09-23 15:23:52
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Normally-off AlGaN/GaN Heterojunction Metal-Insulator-Semiconductor Field-Effect Transistors with Gate-First Process
摘要： In this study, AlGaN/GaN heterojunction metal-insulator-semiconductor field-effect transistors with gate-first process were developed for normally-off operation with p-GaN cap layers and SiNx dielectrics. To avoid the effect of the annealing process on the gate, a low-temperature ohmic contact technique was developed at an annealing temperature of about 500 oC for 20 min in N2 ambient. With the assistance of inductively coupled plasma dry etching, a contact resistance of 1.45 Ω·mm and sheet resistance of 1080.1 Ω/□ were obtained in the recessed region. Owing to the inset of the SiNx layer, the threshold voltage of fabricated device was enhanced to approximately 2 V, and good pinch-off was observed with the gate voltage up to 16 V. Compared with the conventional high-temperature ohmic annealing process, the gate leakage current was suppressed significantly in both reverse and forward directions. Good device performance was confirmed with a maximum channel electron field-effect mobility of 1500 cm2V-1s-1.
关键词： low-temperature ohmic contact,normally-off,gate-first,metal-insulator-semiconductor,AlGaN/GaN HFET
更新于2025-09-23 15:23:52
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[IEEE 2018 IEEE Third Ecuador Technical Chapters Meeting (ETCM) - Cuenca, Ecuador (2018.10.15-2018.10.19)] 2018 IEEE Third Ecuador Technical Chapters Meeting (ETCM) - Reliability in GaN-based devices for power applications
摘要： This paper analyzes two important reliability issues in AlGaN/GaN devices: positive bias temperature instability (PBTI) and time-dependent dielectric breakdown (TDDB). The summarized results of our previous PBTI studies in MOS-HEMTs show that the threshold voltage degradation in devices with SiO2 as gate dielectric is characterized by a universal decreasing behavior of the trapping rate parameter and is ascribed to charge trapping in the SiO2 and at the SiO2/GaN interface. On the contrary, the degradation observed in Al2O3- and AlN/Al2O3-gate stacks is mainly attributed to charge capture in the pre-existing dielectric traps with a negligible interface state generation. Additionally, the insertion of a thin AlN layer impacts on the device reliability because larger trap density, faster charge trapping, wider trap energy distribution and slower charge release are observed compared with devices without this layer. The dielectric importance of GaN-based devices has been also investigated in Schottky Barrier Diodes (SBDs) with a gated edge termination (GET). Our recent TDDB results indicate a narrower Weibull distribution, and a longer time to failure in devices with a double GET layer structure and with a thick passivation layer (2 GET-THICK) than in single GET devices with a thin passivation (1 GET-THIN). Therefore, the former structure is more suitable for high-power and high-temperature applications.
关键词： TDDB,AlGaN/GaN SBD,trapping,de-trapping,reliability,PBTI,breakdown voltage,GET,MOS-HEMT
更新于2025-09-23 15:23:52
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Impact of oxide/barrier charge on threshold voltage instabilities in AlGaN/GaN metal-oxide-semiconductor heterostructures
摘要： Threshold voltage instabilities in AlGaN/GaN metal-oxide-semiconductor (MOS) heterostructures were investigated by means of capacitance-voltage (CV) hysteresis measurement and simulations. We focused on the impact of net charge at oxide/semiconductor interface (Qint) on the CV hysteresis. Our simulations suggest that due to different band bending at the interface, any positive or negative Qint with lower density (in the order of 1012 cm?2) results in a presence of relatively shallow unoccupied oxide/barrier interface states in equilibrium. On the other hand, high density of negative Qint (Qint/q ≈ ?1013 cm?2) results in very deep unoccupied interface states, which in turn leads to incomplete electron re-emission during backward CV sweep and thus increased CV hysteresis of the MOS heterostructures compared to previous case. Impact of Qint is illustrated experimentally on MOS heterostructures with Al2O3 gate dielectric grown by metal-organic chemical vapor deposition, showing Qint of ?1.2 × 1013 and +0.5 × 1012 cm?2 for structures with and without post-deposition annealing, respectively. Our results therefore suggest that normally-off AlGaN/GaN MOS heterostructure field-effect transistors featuring high density of negative Qint can be expected to be more susceptible for threshold voltage instabilities compared to normally-on counterparts.
关键词： MOS,Al2O3 gate dielectric,Heterostructure field-effect transistor,Interface traps,AlGaN/GaN
更新于2025-09-23 15:23:52
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Thermal Analysis of AlGaN/GaN High-Electron-Mobility Transistors with Graphene
摘要： A thermal analysis of AlGaN/GaN high electron mobility transistors (HEMTs) with Graphene is investigated using Silvaco and Finite Element Method. Two thermal management solutions are adopted; first of all, graphene is used as dissipation material between SiC substrate and GaN buffer layer to reduce thermal boundary resistance of the device. At the same time, graphene is also used as a thermal spread material on the top of the source contacts to reduce thermal resistance of the device. The thermal analysis results show that the temperature rise of device adopting graphene decreases by 46.5% in transistors operating at 13.86 W/mm. Meanwhile, the thermal resistance of GaN HEMTs with graphene is 6.8 K/W, which is much lower than the device without graphene, which is 18.5 K/W. The thermal management solutions are useful for integration of large-scale graphene into practical devices for effective heat spreading in AlGaN/GaN HEMT.
关键词： AlGaN/GaN,Thermal Management,High-Electron-Mobility Transistors (HEMTs),Graphene
更新于2025-09-23 15:23:52
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[IEEE 2018 IEEE International Meeting for Future of Electron Devices, Kansai (IMFEDK) - Kyoto, Japan (2018.6.21-2018.6.22)] 2018 IEEE International Meeting for Future of Electron Devices, Kansai (IMFEDK) - Reduced Current Collapse in AIGaN/GaN HEMTs with p-GaN Layer in Gate-Drain Access Region
摘要： For the purpose of reducing current collapse, we have studied a special structure of an AlGaN/GaN HEMT, in which an isolated p-GaN layer is located in the gate-drain access region. An addition of an isolated p-GaN layer resulted in significant suppression in current collapse by 98 %, as compared to the conventional HEMT. It was also found that current collapse was more effectively suppressed when the p-GaN region was located closer to the gate.
关键词： current collapse,HEMT,AlGaN/GaN,p-GaN layer
更新于2025-09-23 15:22:29
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Monolithic integration of E/D-mode GaN MIS-HEMTs on ultrathin-barrier AlGaN/GaN heterostructure on Si substrates
摘要： Monolithically integrated enhancement/depletion-mode (E/D-mode) GaN-based metal–insulator–semiconductor high-electron-mobility transistors (MIS-HEMTs) and inverters, were fabricated on an ultrathin-barrier (UTB) AlGaN/GaN heterostructure grown on Si substrates. By employing a graded AlGaN back barrier in the UTB-AlGaN/GaN heterostructure, a high threshold voltage (VTH) of +3.3 V is achieved in the E-mode MIS-HEMTs. The fabricated MIS-HEMT inverter features a high logic swing voltage of 7.76 V at a supply voltage of 8 V, a small VTH hysteresis as well as deviation less than 0.2 V. The UTB AlGaN/GaN-on-Si technology provides a good platform for integration of MIS-gate-based drivers and power transistors.
关键词： monolithic integration,ultrathin-barrier,GaN,E/D-mode,MIS-HEMT,inverter,AlGaN/GaN heterostructure,Si substrate
更新于2025-09-23 15:22:29
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[IEEE 2018 IEEE International Meeting for Future of Electron Devices, Kansai (IMFEDK) - Kyoto, Japan (2018.6.21-2018.6.22)] 2018 IEEE International Meeting for Future of Electron Devices, Kansai (IMFEDK) - Improved Current Collapse in AlGaN/GaN MOS-HEMTs with Dual Field-Plates
摘要： We fabricated AlGaN/GaN MOS-HEMTs with a dual-field-plate (FP), composed of gate-FP and source-FP. Using pulsed I-V technique, the effect of FP on current collapse was studied. Applying a high positive gate voltage resulted in current collapse suppression. It was found that the use of dual-FP was effective to significantly suppress the current collapse.
关键词： current collapse,MOS,AlGaN/GaN,field-plate
更新于2025-09-23 15:22:29
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MPA-GSH functionalized AlGaN/ GaN High Electron Mobility Transistor based sensor for Cadmium ion detection
摘要： This work demonstrates a novel AlGaN/GaN high electron mobility transistor (HEMT) based cadmium ion (Cd2+) sensor with Mercaptopropionic Acid (MPA) and Glutathione (GSH) functionalization. The sensing response of the sensor was analysed by detecting Cd2+ ions at different concentrations. The AlGaN/GaN HEMT sensor exhibits excellent response with the sensitivity of 0.241 μA/ppb, a fast response time of ~ 3 seconds and a lower detection limit of 0.255 ppb. The observed lower detection limit is significantly lower than the World Health Organization (WHO) standard recommended limit for Cd2+ ions in drinking water. Furthermore, the sensor showed good selectivity of Cd2+ ions towards other heavy metal ions. The results indicate that the binding properties of GSH to Cd and the sensitivity of 2-D electron gas (2DEG) towards the variation of charges at the gate region makes the device highly sensitive with rapid detection of Cd2+ ions.
关键词： MPA,Cd2+ ions,AlGaN/GaN HEMT,sensing,GSH
更新于2025-09-23 15:22:29