High temperature power electronics has become possible with the recent availability of silicon carbide devices. This material, as other wide-bandgap semiconductors, can operate at temperatures above 500°C, whereas silicon is limited to 150-200°C. Applications such as transportation or a deep oil and gas wells drilling can benefit. A few converters operating above 200°C have been demonstrated, but work is still ongoing to design and build a power system able to operate in harsh environment (high temperature and deep thermal cycling).

International audienceThe fabrication of Schottky diodes withstanding breakdown voltages up to 10 kV is demonstrated. A corresponding electric field of 7.7 MV/cm at the center of the diode is evaluated with the help of a two-dimensional finite elements software. These properties result from a net shallow acceptor concentration below 10(16) cm(-3) in the first micrometers of an epitaxial film with optimized crystalline quality and a special oxidizing treatment of its surface, allowing the true dielectric strength of bulk diamond to be revealed

Temperature dependant properties of wide band gap semiconductors have been used to calculate theoretical specific on-resistance, breakdown voltage, and thermal run away temperature in SiC, GaN and diamond, and Si vertical power devices for comparison. It appears mainly that diamond is interesting for high power devices for high temperature applications. At room temperature, diamond power devices should be superior to SiC only for voltage higher than 30-40 kV, due to the high energy activation of the dopants.

International audienceDiamond is a very promising material for power electronics and electrical energy management devices. Several architectures have been implemented in the past for the fabrication of Schottky diodes on boron doped microwave plasma enhanced chemical vapour deposition (MPCVD) layers and on lowly and highly boron doped stacked structures. Meanwhile, the performances often suffered several limitations, mainly due to insufficient crystalline quality of the layers or a non-optimized diamond/metal interface. In this study, we will especially show that the achievement of diamond Schottky diode with high breakdown reverse voltage and high breakdown field goes through the optimization of several factors: a net acceptor concentration below 10(16) cm(-3), the epilayer growth conditions, the implementation of efficient surface passivation techniques and the integrity of the metal/diamond interface. Optimizing the previous conditions enabled us to fabricate a lateral gold Schottky diodes withdrawing reverse voltages up to 7.5 kV before avalanche breakdown induced by an electric field in the range 7-9.5 MV/cm. These findings open the route for unipolar diamond devices operating in high power electronics without the use of guard rings or edge terminations contrary to other wide band gap semiconductors

SiC is currently an important topic in power devices. This new technology leads to lower power losses, faster switching, and higher working temperature. The design of SiC power devices requires the integration of edge termination techniques to obtain a high blocking voltage. The mesa structure approach is one wellestablished method. It could be used alone or in combination with a Junction Termination Extension (JTE). The mesa consists of a structure that removes material around the pn-junction. Due to the strong Si-C bonds, conventional chemical-wet etching solutions are inefficient on SiC, so plasma methods are required to etch SiC.The presented work is based on the use of an RIE reactor with an SF 6 /O 2 plasma. Its geometry structure and parameters were optimized. An etch rate of 0.35 µm/min was obtained without any trenching phenomenon. Trenches deeper than 10 µm deep were realized with a nickel etching mask that shows a high selectivity. AFM analysis revealed an etched surface as smooth as the initial one.

In this paper, the electrical properties of Ti 3 SiC 2 -based ohmic contacts formed on p-type 4H-SiC were studied. The growth of Ti 3 SiC 2 thin films were studied onto 4H-SiC substrates by thermal annealing of Ti-Al layers deposited by magnetron sputtering. In this study, we varied the concentrations of Ti and Al (Ti 20 Al 80 , Ti 30 Al 70 , Ti 50 Al 50 , and Ti), and the annealing temperature from 900°C to 1200°C for each concentration. X-ray diffraction and transmission electron microscopy analyzes were performed on the samples to determine the microstructure of the annealed layers and to further investigate the compounds formed after annealing. Using the transfer length method structures, the specific contact resistance (SCR) at room temperature of all contacts was measured. The temperature dependence up to 600°C of the SCR of the best contacts was studied to understand the current mechanisms at the Ti 3 SiC 2 /SiC interface. The experimental results are in agreement with the thermionic field emission theory. With this model, the barrier height of the contact varies between 0.71 and 0.85 eV. Finally, ageing tests showed that Ti3SiC2-based contacts were stable and reliable up to 400 h at 600°C under Ar.Index Terms-Ohmic contact, silicon carbide (SiC), thermionic field emission (TFE), Ti-Al alloy, Ti 3 SiC 2 .

Current–voltage (I–V) and capacitance–voltage (C–V) characteristics of Schottky Mo/4H-SiC diodes have been measured and analyzed as a function of temperature between 80 and 400 K. The I–V characteristics significantly deviate from ideal characteristics predicted by the thermionic emission model because of the inhomogeneity of Schottky contact. After a brief review of the different existing models, the main parameters (ideality factor, barrier height, and effective Richardson constant) of both diodes have been extracted in the frame of a Gaussian barrier height distribution model, whose mean and standard deviation are linearly dependent on voltage and temperature, as well as in the context of the potential fluctuation model. The results are compared with the values extracted by C–V and the values in the literature. A link is established between these two models. Diodes of different I–V  characteristics, either identified as single barrier or double barrier, have been analyzed by Deep Level Transient Spectroscopy (DLTS) to investigate the deep level defects present. No noticeable difference has been found.

Investigations on Ni-Al alloys to form ohmic contacts on p-type 4H-SiC are presented in this paper. Several ratios of the Ni/Al contact were examined. Rapid thermal annealing was performed in Argon atmosphere at 400°C during 1 minute, followed by an annealing at 1000°C during 2 minutes. In order to extract the specific contact resistance, transmission line method (TLM) test-structures were fabricated. A specific contact resistance of 3×10 -5 Ω.cm 2 was obtained reproducibly on p-type layers, with a doping of NA = 1×10 19 cm -3 performed by Al 2+ ion implantation. The lowest specific contact resistance value measured was 8×10 -6 Ω.cm 2 .