Key Engineering Materials, ISSN: 1662-9795, Vol. 1021, pp 1-6

doi: 10.4028/p-T0Vjdb

© 2025 The Author(s). Published by Trans Tech Publications Ltd, Switzerland.

Submitted:
2024-08-21

Revised:
2025-09-01

Accepted:
2025-09-01

Online:
2025-09-05

Electrical Characterization of HV (10 kV) Power 4H-SiC Bipolar Junction Transistor

The original version of this paper is available on https://www.scientific.net/KEM.1021.1.pdf

Pierre Brosselard , Brenda Fosso-Sob , Dominique Planson , Pascal Bevilacqua , Camille Sonneville , Mihai Lazar , Bertrand Vergne , Sigo Scharnholz and Hervé Morel

INSA Lyon, Université Claude Bernard Lyon 1, Ecole Centrale Lyon, CNRS, Ampère, UMR-5005, F-69621, France

Light, Nanomaterials, Nanotechnologies, L2n, UMR CNRS7076, Université de Technologie de Troyes, 10004, Troyes, France

ISL, French-German Research Institute of Saint Louis, 5 rue Général Cassagnou, 68301 Saint Louis, France

pierre.brosselard@insa-lyon.fr, brenda.fosso-sob@insa-lyon.fr, dominique.planson@insa-lyon.fr, pascal.bevilacqua@insa-lyon.fr, camille.sonneville@insa-lyon.fr, mihai.lazar@utt.fr,

Keywords: 4 H -SiC, Bipolar Junction Transistor, Electrical Characterization, High Voltage

Abstract

In this paper, the static and dynamic characterization of a High Voltage ( 10 kV ) Bipolar Junction Transistor (BJT) is presented. Using a high-voltage source in vacuum conditions, a breakdown voltage of 11 kV was measured. Results showed that both large and small BJTs exhibit similar on-state resistance per unit area and collector current density of 55 A.cm . The current gain increases with a decrease in temperature, indicating reduced charge carrier recombination at lower thermal energies. Also, BJT have been characterized in switching mode at 1 kV . The study concludes that 4 H -SiC BJT demonstrates promising electrical performance for high-efficiency applications in harsh environments.

Introduction

The original version of this paper is available on https://www.scientific.net/KEM.1021.1.pdf

4H-SiC Bipolar Junction Transistors (BJTs) offer significant advantages for high-voltage and hightemperature applications due to their superior characteristics, including low on-state resistance and elevated breakdown voltage [1]-[2]. These devices are highly efficient in various sectors. However, their performance can be affected by temperature change. Therefore, it is very interesting to study its behavior in extreme conditions, especially in high-power applications [3]-[4]. After a short description of the BJT structure, electrical characterization in static mode for a temperature range from up to will be demonstrated. This work reports the switching characteristics of the BJT using a double source test bench which involves providing controlled input pulses to the base while monitoring the response at the collector.

BJT's Structure

The original version of this paper is available on https://www.scientific.net/KEM.1021.1.pdf

The BJTs were designed and fabricated on a wafer with an epilayer of thick and doping concentration of (Fig.1). Mesa with JTE (Junction Termination Extension) and JTE rings has been implemented for the edge termination. Thermal oxidation followed by the deposition of several LPCVD (Low-Pressure Chemical Vapor Deposition) and PECVD (Plasma Enhanced Chemical Vapor Deposition) layers (yellow layer in Fig. 1) and also a thick polymide layer (brown layer in Fig. 1) is used for the device passivation. Three unique configurations of BJTs, each with varying finger length and active area, designed to enhance their electrical performance. The configurations include two distinct finger lengths of and , these lengths were paired with active area, specifically for large devices and for small

BJTs, as detailed in Table 1. A maximum breakdown voltage of 11 kV was obtained in vacuum conditions with a high-voltage source [5].

Fig.1. Cross-section of the studied BJT
Table 1. Summary of the different BJT configurations, square dies

Fig.1. Cross-section of the studied BJT Table 1. Summary of the different BJT configurations, square dies

Finger Length (μm) | Die area (mm²)
420 | 2.12
420 | 15.6
640 | 15.6

Experimental Setup for Static Characteristics

The original version of this paper is available on https://www.scientific.net/KEM.1021.1.pdf

The setup involves the static characterization of BJTs using a B1505A, capable of handling up to 20 A in pulsed mode for the collector, 1 A for the base, and 3 kV in blocking mode, alongside a Thermal Conditioner Thermonics T2500/300E for temperature control from up to . Three samples were characterized with their respective finger length and active area. Measurements include applying a voltage sweep V CE and measuring IC for different fixed values of IB from 0.1 A to 1 A to obtain the output characteristic curves. By analyzing these curves, we can assess the transistor behavior in different operating regions and extract key parameters like, current gain, b.

Results and Analysis of the static characteristics

The original version of this paper is available on https://www.scientific.net/KEM.1021.1.pdf

The small and large BJTs exhibit similar on-state resistance per unit area as shown in Fig. 2 Both devices achieved approximately 55 A.cm for collector current density with comparable base-current densities, to , respectively corresponding to different base currents and 0.5 A respectively). This observation suggests that the active area does not significantly impact the electrical characteristics concerning current density. Therefore, regardless of the physical size of the BJTs, their performance in terms of current density remains the same.
From Fig.3, we can observe that the current gain, b , is very similar between large and small BJTs ( finger length, and finger length, ). A similar trend is noticed between large BJTs with different finger length ( and ), both having a area but there are measured on two different wafers.

Fig. 2. for different at for a small (open symbol) and large (closed symbol) BJT, finger length of

Fig. 2. for different at for a small (open symbol) and large (closed symbol) BJT, finger length of

Fig. 3. Extracted for 4 different BJTs (finger length and area) at

Fig. 3. Extracted for 4 different BJTs (finger length and area) at

Fig. 4. Extracted obtained with a B1505A (quasi static measurements) for the large BJT (finger length , from triangular symbol on Fig. 2) for a temperature range of to

Fig. 4. Extracted obtained with a B1505A (quasi static measurements) for the large BJT (finger length , from triangular symbol on Fig. 2) for a temperature range of to

Additionally, the current gain of the large BJTs tends to increase with decreased temperature as seen in Fig. 4. This increase is as a result of the reduced recombination rate of charge carriers due to lower thermal energy, which means fewer charge carriers recombine, more contribute to the current. It could be also due to higher ionization of p-type doping base. Consequently, a smaller base current is required to control a given collector current, effectively enhancing the transistor's amplification capacity. This implies that at lower temperatures, the BJTs become more efficient in amplifying the base current.

Experimental Setup for Switching Characteristics

The original version of this paper is available on https://www.scientific.net/KEM.1021.1.pdf

Fig. 5. Double pulse test schematic diagram for switching characteristics on the BJTs

Fig. 5. Double pulse test schematic diagram for switching characteristics on the BJTs

To investigate the switching characteristic of the BJTs, a double pulse test circuit was configured as per the provided schematic in Fig. 5. The setup includes a voltage supply (VIN from 100 V to 1000 V ) a base driver is connected to the base of the SiC BJTs. A fast recovery diode and an inductor are used to manage the switching transitions and energy storage respectively. The different voltages (Base, Collector and Emitter), the Base current using a current probe and the collector current using a shunt resistance are measured at each VIN step to analyze the BJT switching performance.

Results and Analysis of the Switching Characteristics

The original version of this paper is available on https://www.scientific.net/KEM.1021.1.pdf

Fig. 6 shows the behavior of and respect to time for the switching characteristics of the BJT samples. Ic exhibits a sharp rise as the BJT turns on due to the inductance charging, reaching higher peaks with increased However, the current starts dropping from its peak indicating that the base current is insufficient to maintain the BJT in saturation mode, leading to a transition towards the linear mode. This is evident in the VCE graph in Fig. 7 where V CE drops rapidly during the initial turn-on and then stabilizes at a higher voltage as the device exhibit saturation.

Fig. 6. Ic and versus time for various steps

Fig. 6. Ic and versus time for various steps

Fig. 7. Vee versus time for various VIN steps

Fig. 7. Vee versus time for various VIN steps

Fig. 8 shows how the current gain ( ) initially spikes, indicating strong carrier injection but then decreases as a reflection of Ic due to the linear mode.

Fig. 8. Extracted versus time for various VIN steps

Fig. 8. Extracted versus time for various VIN steps

Fig. 9. Extracted for 3 different BJTs (finger lengths)

Fig. 9. Extracted for 3 different BJTs (finger lengths)

Fig. 9 shows the variation of extracted versus time for the 3 different large BJTs. A similar is obtained between these 3 different BJTs. The values (17 and 18) are very similar to those obtained in the static mode (Fig. 3, 15 and 18). We can therefore conclude that the finger length and size have no impact on the current gain of the device even if it extracted in static or dynamic mode.

Summary

The original version of this paper is available on https://www.scientific.net/KEM.1021.1.pdf

This paper presents the static and dynamic characteristics of BJTs, which demonstrates promising electrical performance, making it suitable for high-efficiency applications in harsh environments and their performance improves at lower temperatures due to enhanced carrier dynamics. Similar extracted have been obtained for both static and dynamic mode even with different finger lengths and areas of the BJTs.

Acknoledgments

The original version of this paper is available on https://www.scientific.net/KEM.1021.1.pdf

Authors thank the French Research National Agency (ANR) for financial support of HV-PhotoSw: ANR-18-CE05-0020-01

References

The original version of this paper is available on https://www.scientific.net/KEM.1021.1.pdf

B. Asllani, P. Bevilacqua, H. Morel, D. Planson, L. V. Phung, B. Choucoutou, T. Lagier, and M. M. Guyennet "Static and Switching Characteristics of 10 kV -class Silicon Carbide Bipolar Junction Transistors and Darlingtons" Materials Science Forum Vol. 1004 (2020) pp 923-932

M. Nawaz, N. Chen, F. Chimento and L. Wang "Static and Dynamic Characterization of HighPower Silicon Carbide BJT Module" 2014 IEEE Energy Conversion Congress and Exposition (ECCE), Pittsburgh, PA, USA, 2014, pp. 2824-2831

M. Hosseinzadehlish, S. Jahdi, C. Shen, X. Yuan, I. Laird, O. Alatise, J. O. Gonzalez "Impact of Temperature and Base Bias Stress on the Static Characteristic of Silicon and 4H-SiC NPN Vertical BJTs" PCIM Europe 2023; International Exhibition and Conference for Power Electronics, Intelligent Motion, Renewable Energy and Energy Management, Nuremberg, Germany, 2023, pp. 1-9

M.M.R. Ahmed, N-A.Parker-Allotey, P.A. Mawby, M. Nawaz and C. Zaring "Characterization of the Static and Dynamic Behavior Of A SiC BJT" 2008 13th International Power Electronics and Motion Control Conference, Poznan, Poland, 2008, pp. 2472-2477

A. Ammar, M. Lazar, B. Vergne, S. Scharnholz, L. V. Phung, P. Brosselard, D. Tournier, C. Sonneville, C. Raynaud, M. Zielinski, and al. "Design Fabrication and characterization of 10 KV 4H-SiC BJT for Phototransistor Target. 2023 - Romanian Journal of Information Science & Technology - Vol.26, , pp 193-204

This ePub file was created using machine-generated methods and automated software to convert the source text into an ePub format and may contain formatting inconsistencies from the original version. Formatting may vary depending on the device used.