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

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

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This paper deals with the characterization of SiC devices by optical beam induced currents (OBIC). OBIC is a technique that measures a photocurrent in response to a fine UV laser beam that is scanned laterally over the surface of the device. In this way a number of important material and device parameters can be derived. We concentrate here on three aspects, the field profile in reverse biased diodes with particular emphasis on field terminating issues at the device edges under high reverse voltages; the minority carrier lifetimes in 6H‐SiC; and the determination of ionization coefficients for electrons and holes in 6H‐SiC. The latter are important material parameters for the modelling of high power devices and determine their break‐through voltage. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Optical Beam Induced Current (OBIC) measurements have been performed on 4H-SiC avalanche diodes with very thin and highly doped avalanche region. The light source used in this study is an Ar-laser with a wavelength of 351 nm which results in a mixed carrier injection. From these measurements, impact ionization coefficients for 4H-SiC have been extracted in the electric field range from 3 to 4.8 MV/cm. In combination with ionization coefficients in our previous paper extracted from diodes with lowly doped avalanche region, we propose a set of parameters of impact ionization coefficients for 4H-SiC, applicable to a wide electric field range.