Field Plate Structure Research Articles

Design and analysis of novel field plate-trench composite anode terminal in high-voltage Ga2O3 Schottky Barrier diode

Abstract To improve the breakdown voltage of Ga2O3 vertical Schottky Barrier diode (SBD), this article innovatively proposes a novel field plate-trench composite structure. Different from the traditional field plate structures and trench structures, the proposed composite structure innovatively adds a shallow trench under the field plate structure, greatly reducing the depth of the trench and relieving the etching difficulty. At the same time, simulation results show that the field plate-shallow trench composite structure can increase the breakdown voltage of the device from 543 V to 952 V, which is nearly 1.76 times higher than that of traditional devices. The new field plate-trench composite structure greatly improves the breakdown voltage of Ga2O3 vertical SBD, while also increasing the forward characteristics and the reliability of the device, having superiority in size, and alleviating the difficulty of the process. Our research work also has guiding significance for the research of other wide bandgap power devices.

AI‐assisted Field Plate Design of GaN HEMT Device

AbstractGaN High Electron Mobility Transistors (HEMTs) plays a vital role in high‐power and high‐frequency electronics. Meeting the demanding performance requirements of these devices without compromising reliability is a challenging endeavor. Field Plates are employed to redistribute the electric field, minimizing the risk of device failure, especially in high‐voltage operations. While machine learning is applied to GaN device design, its application to field plate structures, known for their geometric complexity, is limited. This study introduces a novel approach to streamlining the field plate design process. It transforms complex 2D field plate structures into a concise feature space, reducing data requirements. A machine learning‐assisted design framework is proposed to optimize field plate structures and perform inverse design. This approach is not exclusive to the design of GaN HEMTs and can be extended to various semiconductor devices with field plate structures. The framework combines technology computer‐aided design (TCAD), machine learning, and optimization, streamlining the design process.

Research on the Gunn Oscillation Effect of GaN HEMT with Field Plate Structure in the Terahertz Frequency Band

Based on the enormous application potential of GaN-based high electron mobility transistors (HEMT) in high-frequency and high-power scenarios, this article focuses mainly on the study of the Gunn oscillation effect of GaN-based HEMT devices. From the perspective of electric field regulation, a sandwich structure GaN HEMT device model with field plate structure is proposed, and a hydrodynamic physical model is established. The negative resistance characteristics in the GaN HEMT are obtained by the finite element method and the influence of the gate field plate on the Gunn oscillation frequency in the device channel is studied. The numerical simulation results show that the suitable field plate structure can modulate the distribution of the channel electric field below the gate, promote the electric field to enter the negative differential mobility region, undergo valley to valley electron transfer, form electron domains, and generate the Gunn oscillation currents in the terahertz band. Meanwhile, the length of the field plate regulates the oscillation current frequency of the device, and the stable and usable terahertz frequency band signal can be realized. This research opens up the possibility for semiconductor solid-state devices to realize terahertz frequency band radiation, and provides the basis for realizing new breakthroughs in HEMT for terahertz applications.

A 1.6 kV Ga2O3 Schottky Barrier Diode with a Low Reverse Current of 1.2 × 10-5 A/cm2 Enabled by Field Plates and N Ion-Implantation Edge Termination.

In this work, by employing field plate (FP) and N ion-implantation edge termination (NIET) structure, the electrical performance of the β-Ga2O3 Schottky barrier diode (SBD) was greatly improved. Ten samples of vertical SBDs were fabricated to investigate the influence of the relative positions of field plates (FPs) and ion implantation on the device performance. The device with the FP of 15 μm and the ion implantation at the edge of the Schottky electrode exhibited a breakdown voltage (Vbr) of 1616 V, a specific on-resistance (Ron,sp) of 5.11 mΩ·cm2, a power figure of merit (PFOM) of 0.511 GW/cm2, and a reverse current density of 1.2 × 10-5 A/cm2 @ -1000 V. Compared to the control device, although the Ron,sp increased by 1 mΩ·cm2, the Vbr of the device increased by 183% and the PFOM increased by 546.8%. Moreover, the reverse leakage current of the device with the FP and NIET structure decreased by three orders of magnitude. The TCAD simulation revealed that the peak electric field at the interface decreased from 7 MV/cm @ -500 V to 4.18 MV/cm @ -1000 V. These results demonstrate the great potential for the β-Ga2O3 SBD with a FP and NIET structure in power electronic applications.

Novel double deck gate field plate structure on a normally-off AlGaN/GaN HEMT- An extensive analysis

A novel double deck gate field plate structure on a normally-off AlGaN/GaN HEMT is proposed and compared with the conventional no field plate structure. Several passivation materials with relative permittivity (εr) ranging from 3.9 to 22 is taken into consideration to study the breakdown and DC characteristics. The implementation of field plate along with a higher εr material helps in improving breakdown voltage (VBr) as they both decrease the electric field at the gate's drain edge. Aiming device optimization several field plate configurations are studied including tri field plate structure, dual field plate structures and single gate FP structure. Extensive analysis in these structures are done with different lengths of the field plates and distance between source and drain. Distance between source and drain (LSD) is varied from 8.4 to 13.4 μm, source FP lengths (LS_FP) varies from 1 to 7 μm, gate FP lengths (LG_FP) varies from 0.9 to 2.3 μm and drain FP lengths (LD_FP) varies from 0.2 to 4.9 μm. In all scenarios with varying LSD, VBr rises with increasing LSD. For source, gate and drain FP lengths variation, VBr decreases as it gets longer because the electric field becomes very high. As the distance between the FP edge and the drain becomes narrower with increase in FP lengths, the breakdown occurs at lower voltage. At LSD 13.4 μm, this novel double deck gate FP structure with conventional drain field plate structure gives highest VBr of 1660 V and a small Ron of 2.39 Ω mm as compared to other structures. It also outperforms the other three structures in FT (9.84 GHz) at this particular LSD. Analysis of the simulated structures shows that the union of gate-drain field plate boosts the VBr while decreasing the Ron, resulting in improved electrical performance and a wider application range.

Simulation Research on High-Voltage β-Ga2O3 MOSFET Based on Floating Field Plate

The simulation model of a depletion-mode (D-mode) β-Ga2O3 metal–oxide–semiconductor field-effect transistor (MOSFET) is constructed by Silvaco ATLAS technology computer-aided design (TCAD) simulation, which employs an epitaxial drift layer grown on a sapphire substrate. On this basis, the floating field plate (F-FP) structure based on the gate-pad-connected field plate (P-FP) is proposed to improve the breakdown characteristics of the device, which is easy to be prepared. The working principle of F-FP is investigated with the help of the device with one F-FP. Based on the principle that the number of floating field plates is increased on an optimized floating field plate structure. Subsequently, the devices with two and three floating field plates are simulated in turn, and the optimal structural parameters of the three F-FPs device are finally obtained, and the breakdown voltage is 3800 V at this time. In addition, it is found that the device breakdown voltage is increased by approximately 500–600 V for each additional floating field plate.

A high-breakdown-voltage β-Ga2O3 nanoFET with a beveled field-plate structure

The three-terminal off-state breakdown voltage of the β-Ga2O3 nanoFET with beveled field-plate (FP) was obtained at +441 V, enhanced by downstream plasma-etched 60° h-BN FP structure.

Design of a lateral photoconductive semiconductor switch with a low resistivity region on semi-insulating GaN to enhance breakdown characteristics

The breakdown characteristics of the semi-insulating lateral GaN photoconductive semiconductor switches (PCSS) with low resistivity region (LRR) structure were simulated. The design, which can reduce the peak electric field by adjusting the electric field distribution for PCSS, was first proposed. In comparison to conventional field plate and n-type doping below the electrode structures, the LRR structure robustly enhances the breakdown characteristics of PCSS while reducing the influence of on-state characteristics. The impact of different structural parameters on the breakdown voltage and on-state characteristics was investigated. In the case of a small size device with a 5 μm electrode gap, the LRR structure is able to decrease the peak electric field by 54 % at 400 kV/cm and increase breakdown voltage by 45 %. When the electrode gap is increased to 0.25 mm, under a bias voltage of 5 kV, the field plate structure can reduce the peak electric field by 35 %, but the LRR structure can reduce the peak electric field by 42 %. When applied a voltage of 2 kV, the PCSS with the LRR structure triggered by a laser pulse with a wavelength of 532 nm and an energy of 265 μJ has a minimum on-resistivity being less than 0.5 Ω cm and the resistivity ratio between the off and on states reaching up to 1 × 108.

Influence of Gate Work Function on Electrical Characteristics of a-IGZO TFT with Field Plate Structure

Influence of Gate Work Function on Electrical Characteristics of a-IGZO TFT with Field Plate Structure

Design of Trench MIS Field Plate Structure for Edge Termination of GaN Vertical PN Diode.

In this study, we developed an analytic model to design a trench metal-insulator-semiconductor (MIS) field plate (FP) structure for the edge termination of a vertical GaN PN diode. The key parameters considered in the trench MIS FP structure include trench depth, MIS dielectric material and thickness, and interface charge density of MIS. The boundary conditions are defined based on the maximum allowed electric field strengths at the dielectric and semiconductor regions. The developed model was validated using TCAD simulations. As an example, a 1 kV GaN vertical PN diode was designed using the optimized FP structure, which exhibited the same breakdown voltage characteristics as an ideal one-dimensional PN diode structure without edge effects. This proposed simple analytic model offers a design guideline for the trench MIS FP for the edge termination of vertical PN diodes, enabling efficient design without the need for extensive TCAD simulations, thus saving significant time and effort.

Simulation studies of floating field plate in β-Ga2O3 power devices and modules

In this work, we present the floating field plate (FFP) that a novel structure modulates the electric field in beta gallium oxide (β-Ga2O3) power devices and integrated circuit modules. By reducing the peak electric field during reverse high-voltage operation, the FFP improves the device's performance while maintaining its forward characteristics. Compared with the traditional field plate structure, the FFP increases the power figure of merit by 34.9% with the same device parameters and reduces the dielectric material requirement by 52% as the same device blocking voltage. We also establish a relationship between different dielectric materials (SiO2, Al2O3, Si3N4, etc.) and the optimal structure size through simulation. More importantly, the FFP can be applied to β-Ga2O3 power modules and optimize the electric field distribution regionally, thereby improving the system’s robustness. This study provides a new solution for enhancing the performance of β-Ga2O3 devices and advancing β-Ga2O3 power modules.

Demonstration of N-Polar All-AlGaN High Electron Mobility Transistors With 375 mA/mm Drive Current

Devices made from ultrawide bandgap (UWBG) materials are being widely investigated for high-power and radio frequency (RF) electronics. High electron mobility transistor (HEMT) is one of the most effective designs to implement heterostructures in III-Nitrides and III-Oxides that leverage a 2D-channel with high conductivity and large breakdown electric field. Nitrogen (N)-polarity in GaN channel HEMTs have shown remarkable performance advantage in both power and RF applications compared to its metal-polar counterpart. Here, UWBG N-polar AlGaN channel HEMT can bring further performance benefits due to an increase in the channel’s breakdown electric field. In this work, we report the first experimental demonstration of N-polar all-AlGaN HEMT devices with two different Al compositions (20% and 30%) in the channel. The HEMT with 3 μm long-channel (20% Al) showed a drive current of 375 mA/mm (at 0 V gate voltage). These devices also show low on-state leakage current of ~0.5 nA/mm, and large on/off ratio of ~2 x 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">8</sup> . Furthermore, >400 V breakdown voltage was achieved without any field plate structures.

Optimization of Dual Field Plate AlGaN/GaN HEMTs Using Artificial Neural Networks and Particle Swarm Optimization Algorithm

Field plate technology is an effective method for improving the breakdown performance of AlGaN/GaN high electron mobility transistor (HEMT). Currently, field plate optimization relies on TCAD simulation, which is time-consuming and difficult to converge. In this study, we propose a fast and efficient method to optimize the gate-source dual field plate (dual-FP) to improve the breakdown performance of the HEMT. Specifically, an artificial neural network (ANN) model was used to fit the relationship between the dual-FP structure parameters and the breakdown voltage (BV), so that the breakdown performance could be predicted quickly and the average prediction error was only 3.06%. Furthermore, the trained ANN model was applied to the particle swarm optimization (PSO) algorithm and a dual-FP HEMT with a breakdown voltage of 1228 V was obtained by optimization. The proposed method shows significant advantages in terms of optimization efficiency and can realize automatic optimization. It also provides a reference for the optimization of other field plate structures of microelectronic devices.

Simulation Optimization of AlGaN/GaN SBD with Field Plate Structures and Recessed Anode.

This study investigated several AlGaN/GaN Schottky Barrier Diodes (SBDs) with different designs to achieve device optimization. First, the optimal electrode spacing, etching depth, and field plate size of the devices were measured using Technology Computer-Aided Design (TCAD) software by Silvaco, and analysis of the electrical behavior of the device was based on the simulation results, and several AlGaN/GaN SBD chips were designed and prepared. The experimental results revealed that the recessed anode can increase the forward current and reduce the on-resistance. An etched depth of 30 nm could obtain a turn-on voltage of 0.75 V and a forward current density of 216 mA/mm. A breakdown voltage of 1043 V and a power figure of merit (FOM) value of 572.6 MW/cm2 was obtained with a 3 μm field plate. Experiments and simulations confirmed that the recessed anode and field plate structure could increase the breakdown voltage and forward current and improve the FOM value, resulting in higher electrical performance and a wider range of application scenarios.

β-Ga2O3 junction barrier Schottky diode with NiO p-well floating field rings

Recently, β-Ga2O3, an ultra-wide bandgap semiconductor, has shown great potential to be used in power devices blessed with its unique material properties. For instance, the measured average critical field of the vertical Schottky barrier diode (SBD) based on β-Ga2O3 has reached 5.45 MV/cm, and no device in any material has measured a greater before. However, the high electric field of the β-Ga2O3 SBD makes it challenging to manage the electric field distribution and leakage current. Here, we show β-Ga2O3 junction barrier Schottky diode with NiO p-well floating field rings (FFRs). For the central anode, we filled a circular trench array with NiO to reduce the surface field under the Schottky contact between them to reduce the leakage current of the device. For the anode edge, experimental results have demonstrated that the produced NiO/β-Ga2O3 heterojunction FFRs enable the spreading of the depletion region, thereby mitigating the crowding effect of electric fields at the anode edge. Additionally, simulation results indicated that the p-NiO field plate structure designed at the edges of the rings and central anode can further reduce the electric field. This work verified the feasibility of the heterojunction FFRs in β-Ga2O3 devices based on the experimental findings and provided ideas for managing the electric field of β-Ga2O3 SBD.

Printed 700 V/V Gain Amplifiers Based on Organic Source‐Gated Transistors with Field Plates

AbstractPrinted amplifiers are promising components for flexible and wearable devices. The circuits need to have small footprint, high amplification, and low power consumption, which is not simultaneously possible with conventional thin‐film transistors because multiple stages are required and introduce sources of variability, failure, or wasted area. Source‐gated transistors (SGTs) can in principle have extremely high intrinsic gain but this is not always the case because of lateral field control problems. A good solution is the use of field plate structures, which are straightforward to implement with top contacts but not so with bottom contacts. Here, a printed implementation of organic SGT with a field plate is presented, which can achieve a record high intrinsic gain of 920 V/V. The single‐stage common‐source amplifier with two organic SGTs also exhibits a high gain of 700 V/V. Simulations confirm the effectiveness of the printed field plate, making it a promising approach for future flexible and wearable electronics.

Analysis of single event effects by heavy ion irradiation of Ga2O3 metal–oxide–semiconductor field-effect transistors

The model of lateral β-Ga2O3 metal–oxide–semiconductor field-effect transistor (MOSFET) was established using Sentaurus Technology Computer Aided Design software. The gate-to-drain distance of the device was 13.7 μm, and the breakdown voltage was 1135 V. The single event effect simulation model caused by heavy ion irradiation was introduced, and the effects of heavy ions’ incident position, angle, drain bias voltage, and linear energy transfer on the single event effect were studied. It is found that x = 7.7 μm is the sensitive location of the single event effect at the gate corner near the drain side and the peak value of the transient current is 177 mA/mm. The effect of the terminal structure of the field plate on the transient effect of the single event effect of β-Ga2O3 MOSFET is studied. It is also found that the sensitive position of the single event effect of the conventional structure, gate-field plate structure, and gate–source composite field plate structure is around x = 7.7 μm when VDS = 10 V. The peak transient currents obtained are 177, 161, and 148 mA/mm. The single event effect pulse current of the three structures increases with an increase in the drain bias voltage, while the peak pulse current of the conventional structure is larger than that of the gate-field plate structure and the gate–source composite structure. The research shows that the terminal structure of the field plate is reliable means to reduce the single particle effect.

Design of normally-off p-GaN/AlGaN/GaN heterojunction field-effect transistors with re-grown AlGaN barrier

In this paper, a novel p-GaN/AlGaN/GaN HFET with re-grown AlGaN is designed by using Silvaco TCAD. It demonstrates that a thin AlGaN barrier with relatively small Al content beneath the p-GaN positively shifts the threshold voltage and helps to obtain normally-off operation, while it also degrades the drain current obviously due to the low 2DEG concentration. On the other hand, the re-grown AlGaN barrier in the access regions can recover the 2DEG concentration and enhance the drain current partially. In addition, the field plate structure formed during the AlGaN re-growth process is beneficial to suppress the electric filed crowding and premature breakdown effectively under forward gate bias. By optimizing the device parameters, normally-off p-GaN/AlGaN/GaN HFET with balanced output current, threshold voltage and breakdown voltage is designed.

Simulation of High Breakdown Voltage, Improved Current Collapse Suppression, and Enhanced Frequency Response AlGaN/GaN HEMT Using A Double Floating Field Plate

In this paper, DC, transient, and RF performances among AlGaN/GaN HEMTs with a no field plate structure (basic), a conventional gate field plate structure (GFP), and a double floating field plate structure (2FFP) were studied by utilizing SILVACO ATLAS 2D device technology computer-aided design (TCAD). The peak electric fields under the gate in drain-side can be alleviated effectively in 2FFP devices, compared with basic and GFP devices, which promotes the breakdown voltage (BV) and suppresses the current collapse phenomenon. As a result, the ON-resistance increase caused by the current collapse phenomena is dramatically suppressed in 2FFP ~19.9% compared with GFP ~49.8% when a 1 ms duration pre-stress was applied with Vds = 300 V in the OFF-state. Because of the discontinuous FP structure, more electric field peaks appear at the edge of the FFP stacks, which leads to a higher BV of ~454.4 V compared to the GFP ~394.3 V and the basic devices ~57.6 V. Moreover, the 2FFP structure performs lower a parasitic capacitance of Cgs = 1.03 pF and Cgd = 0.13 pF than those of the GFP structure (i.e., Cgs = 1.89 pF and Cgd = 0.18 pF). Lower parasitic capacitances lead to a much higher cut-off frequency (ft) of 46 GHz and a maximum oscillation frequency (fmax) of 130 GHz than those of the GFP structure (i.e., ft = 27 GHz and fmax = 93 GHz). These results illustrate the superiority of the 2FFP structure for RF GaN HEMT and open up enormous opportunities for integrated RF GaN devices.

Performance enhancement for AlGaN/GaN HEMTs with dual discrete field-plate

We propose optimized field plate structures to improve the performance of AlGaN / GaN HEMT under electrical stress. The two structures are T-gate AlGaN / GaN HEMT with dual discrete field plates (DDFP-HEMT) and single discrete field-plate (SDFP-HEMT). Benefiting from the modulation effects of the field plate on the electric field, the DDFP-HEMT and SDFP-HEMT exhibit better breakdown characteristics and current collapse suppression. The performance of the two structure devices and no-discrete-field-plate devices (NDFP- HEMT) is explored in Silvaco TCAD. The DDFP-HEMT and SDFP-HEMT achieve the highest off-state breakdown voltage (VBD) of 1188 V and 1120 V in the experiment, respectively, being 33 % and 25 % higher than that of NDFP-HEMT, respectively. In particular, the current collapse in DDFP-HEMT and SDFP- HEMT is reduced by 24 % and 9 % under 200 V stress bias, respectively, when compared to NDFP-HEMT. The DDFP-HEMT shows greatest reliability improvement in the three samples.