An assessment of contact metallization for high power and high temperature diamond Schottky devices

Different metals W, Al, Ni and Cr were evaluated as Schottky contacts on the same p-type lightly boron doped homoepitaxial diamond layer. The current–voltage (I–V) characteristics, the series resistance and the thermal stability are discussed in the range of RT to 625 K for all Schottky devices. High current densities close to 3.2 kA/cm2 are displayed and as the series resistance decreases with increasing temperature, proving the potential of diamond for high power and high temperature devices. The thermal stability of metal/diamond interface investigated with regards to the Schottky barrier height (SBH) and ideality factor n fluctuations indicated that Ni and W are thermally stable in the range of RT to 625 K. Current–voltage measurements at reverse bias indicated a maximum breakdown voltage of 70 V corresponding to an electric field of 3.75 MV/cm. Finally, these electrical measurements have been completed with mechanical adhesion tests of contact metallizations on diamond by nano-scratching technique. These studies clearly reveal Ni as a promising contact metallization for high power, high temperature and good mechanical strength diamond Schottky barrier diode applications

Study of 6H-SiC high voltage bipolar diodes under reverse biases

International audienceSilicon carbide presents electrical properties suitable for many applications especially for high voltage devices. 6H-SiC P+NN+ structures have been fabricated following ISE software simulations in order to block voltages as high as 1.5 kV. In particular, these diodes are realized by surrounding the emitter by a p-type region called junction termination extension (JTE). Electrical characterizations under reverse bias at, room temperature and in various environments (air, silicone oil) show a premature breakdown for the protected diodes. This breakdown is localized at the emitter periphery. Optical beam induced current (OBIC) measurements show a peak of photocurrent at the junction edge, indicating the presence of a high electric field. These results show a protection efficiency of 60% of the JTE. An electrical activation of the aluminum dopants implanted in the JTE around 30% is derived from the analysis of the presented results

Etude de la tenue en tension des dispositifs de puissance en carbure de silicium par caractérisations OBIC et électriques.

Cette étude en vue de l\u27augmentation de la tenue en tension des composants de puissance en carbure de silicium a porté à la fois sur la détermination de certains paramètres physiques du matériau (coefficients d\u27ionisation des électrons et des trous) et sur l\u27analyse du comportement sous polarisation inverse de diodes bipolaires. Les caractérisations électriques ont été complétées par des mesures OBIC (Optical Beam Induced Current). Le début de ces travaux de thèse a été consacré à la mise en place du banc de mesures expérimental OBIC en tenant compte des spécificités du matériau. L\u27étude bibliographique de différentes méthodes d\u27extraction des coefficients d\u27ionisation dans d\u27autres matériaux a conduit à envisager une procédure adaptée au SiC et visant à minimiser les erreurs engendrées par les hypothèses simplificatrices. Pour cela nous avons conçu et réalisé un composant spécifique (diode Schottky à grille semi-transparente) qui permet d\u27évaluer les coefficients d\u27ionisation à partir des variations du facteur de multiplication (M) en fonction de la tension inverse appliquée, obtenues par mesures OBIC. Les paramètres de ce dispositif protégé par extension latérale de jonction implantée ont été optimisés par simulation à l\u27aide du logiciel ISE. L\u27étude des comportements électriques de plusieurs lots de diodes 1,5 kV dont les protections (JTE) ont été réalisées avec des dopants différents (Bore ou Aluminium) a révélé l\u27impact de différentes configurations de recuit post-implantation ionique sur la tenue en tension et sur le comportement en direct. Le banc de mesures OBIC s\u27est avéré efficace dans l\u27étude de la répartition du champ électrique des structures étudiées, il a notamment révélé l\u27influence de divers paramètres (profil de dopage de l\u27émetteur, dopage de la JTE) sur le claquage des composants en SiC. La dernière étape de ces travaux de thèse visant à l\u27augmentation de la tenue en tension a été la réalisation et la caractérisation de diodes conçues pour tenir une tension de 5 kV

Field plate termination for high voltage diamond Schottky diode

International audienceNew field plate architecture is applied to pseudo vertical diamond Schottky diode. New topology structure has been proposed and simulated using Sentaurus TCAD simulation in order to minimize the maximum electric field in the dielectric at high voltage operation. Firstly and after simple variations in the field plate architecture, the breakdown voltage was improved from 1632 V to 2141 V at 700 K. Concerning Emax in the dielectric, we obtained high decreasing of the maximum electric field following the policy of pressure distribution

Conception de transistors MOS haute tension (1200 Volts) pour l'électronique de puissance

TOULOUSE3-BU Sciences (315552104) / SudocSudocFranceF

Field plate termination for high voltage diamond Schottky diode

International audienceNew field plate architecture is applied to pseudo vertical diamond Schottky diode. New topology structure has been proposed and simulated using Sentaurus TCAD simulation in order to minimize the maximum electric field in the dielectric at high voltage operation. Firstly and after simple variations in the field plate architecture, the breakdown voltage was improved from 1632 V to 2141 V at 700 K. Concerning Emax in the dielectric, we obtained high decreasing of the maximum electric field following the policy of pressure distribution

New termination architecture for 1700 V diamond schottky diode

International audienceNew field plate architecture is applied to pseudo vertical diamond Schottky diode. Using several field plate architectures, a TCAD simulation is realized in order to reduce the electric field in the dielectric while maintaining high breakdown voltage. Firstly and after simple variations in the field plate architecture, the breakdown voltage was improved from 1632 V to 2141 V at 700 K. Concerning Emax in the dielectric, we obtained a decreasing of maximum electric field from 57 to 18 MV/cm

Amélioration des performances du thyristor à l'état bloqué en haute température

National audienceNous présentons dans cet article une architecture thyristor silicium présentant de meilleures caractéristiques à l'état bloqué en haute température. L'amélioration de la tenue en tension, par rapport à un thyristor classique, est rendue possible par une utilisation judicieuse de contacts Schottky sur la face arrière d'un thyristor classique. La présence d'un tel contact permet de réduire l'injection de trous de l'émetteur P+ face arrière dans la base N-, et par conséquent de diminuer le courant de fuite à l'état bloqué et ainsi améliorer la tenue en tension directe à températures élevées. Nous étudions, à partir de simulation TCAD, l'effet de la technique sur une structure thyristor 5 kV symétrique en tension sur ses caractéristiques électriques que nous comparerons à celles d'une structure thyristor classiques et à courtscircuits d'anode

Impact of a backside Schottky contact on the thyristor characteristics at high temperature

International audienceIn this paper, a thyristor structure presenting improved electrical characteristics at high temperature is analysed through 2D physical simulations. The replacement of the P emitter of a standard symmetrical thyristor by a judicious association of P diffusions and Schottky contacts at the anode side contributes to the reduction of the leakage current in the forward direction and hence improves the forward blocking voltage at high temperature. A fine-tune of the anode side configuration will improve the forward off-state behaviour with only a negligible on-state voltage drop degradation. Moreover, the comparison with the conventional anode short thyristor shows that the insertion of Schottky contacts leads to the same improvements that the anode short in terms of off-state characteristics, while keeping the reverse blocking capability

Analysis and Optimization of a Thyristor Structure Using Backside Schottky Contacts Suited for the High Temperature

International audienceIn high current, high voltage, high temperature (T > 125 °C) power applications, commercially available conventional silicon thyristors are not suited because they present high leakage current. In this context, this paper presents a high-symmetrical (voltage) thyristor structure that presents a lower leakage current and higher breakover voltage as compared with the conventional thyristor at T > 125 °C. It is shown through 2-D physical simulations that the replacement of the P-emitter of a standard symmetrical thyristor by a judicious association of P diffusions and Schottky contacts at the anode side contributes to the reduction of the leakage current in the forward blocking state at high temperature. A fine tune of the anode side configuration will improve the forward OFF-state behavior with only a negligible ON-state voltage drop degradation. Moreover, the comparison with the conventional anode short thyristor shows that the insertion of Schottky contacts leads to the same improvements in terms of OFF-state forward break over voltage and leakage current and also presents a high reverse blocking voltage