Foreword

This work reports on the performances of ohmic contacts fabricated on highly p-type doped 4H-SiC epitaxial layer selectively grown by vapor-liquid-solid transport. Due to the very high doping level obtained, the contacts have an ohmic behavior even without any annealing process. Upon variation of annealing temperatures, it was shown that both 500 and 800 °C annealing temperature lead to a minimum value of the Specific Contact Resistance (SCR) down to 1.3×10−6 Ω⋅cm2. However, a large variation of the minimum SCR values has been observed (up to 4×10−4 Ω⋅cm2). Possible sources of this fluctuation have been also discussed in this paper

Low temperature (down to 450° C) annealed TiAl contacts on N-type gallium nitride characterized by differential scanning calorimetry

International audienceThis work reports on Differential Scanning Calorimetry (DSC) measurements performed on Ti-Al metallic layers stacks deposited on n+-GaN. The aim is to get better understanding of the mechanisms leading to ohmic contact formation during the annealing stage. Two exothermic peaks were found, one below 500°C and the other one around 660°C. They can be respectively attributed to Al3Ti and Al2Ti compounds formation. The locations of these peaks provide clear evidence of solid-solid reac-tions. Lowest contact resistance is well correlated with the presence of Al3Ti compound, corresponding to Al(200nm)/Ti(50nm) stoichiometric ratio. Subsequently, Al(200 nm)Ti(50 nm) stacks on n+-GaN were annealed from 400°C to 650°C. Specific Contact Resistivity (SCR) values stay in the mid 10-5 Ω.cm² range for annealing temperatures between 450°C and 650°C. Such low-temperature annealed contacts on n+-GaN may open new device processing routes, simpler and cheaper, in which Ohmic and Schottky contacts are annealed together

Application of UV photoluminescence imaging spectroscopy for stacking faults identification on thick, lightly n-type doped, 4°-off 4H-SiC epilayers

This paper deals with the description and the application of an original photoluminescence (PL) imaging technique on thick, lighly n-type doped 4H-SiC epilayers for in-grown stacking fault (SF) identification. This technique, call “photoluminescence imaging spectroscopy” (PLIS), compares different PL imaging pictures in order to create a new picture which displays the location and an approximation of the maximum photoemission wavelength of SFs at room temperature. Five types of SF have been detected and identified by PLIS on two different wafers. The origin of SF type modification during the growth is also discussed in this work

Study and optimization of a 600V Pseudo-vertical GaN-on-silicon rectifier by finite elements simulation

International audienceReal performance breakthrough have been demonstrated for high voltage, high power, high temperature and high frequency devices by using wide band-gap semiconductors, such as 4H-SiC, GaN and AlGaN, over the previously existing devices based on group-IV and III-V lower band-gap semiconductor material. One of the key devices for high power switching converter is a fast rectifier. 4H-SiC based Schottky diodes are now commercially available from many companies with breakdown voltage up to 1,7 kV. However, bulk SiC substrates are very expensive and the hetero-epitaxial SiC layers on low cost substrates have too many crystal defects. These are the main reasons for the ongoing research programs toward GaN based-rectifiers on Silicon substrate for medium voltage range applications (600 V < Vbr < 1.2 kV)

Study and optimization of a 600V Pseudo-vertical GaN-on-silicon rectifier by finite elements simulation

International audienceReal performance breakthrough have been demonstrated for high voltage, high power, high temperature and high frequency devices by using wide band-gap semiconductors, such as 4H-SiC, GaN and AlGaN, over the previously existing devices based on group-IV and III-V lower band-gap semiconductor material. One of the key devices for high power switching converter is a fast rectifier. 4H-SiC based Schottky diodes are now commercially available from many companies with breakdown voltage up to 1,7 kV. However, bulk SiC substrates are very expensive and the hetero-epitaxial SiC layers on low cost substrates have too many crystal defects. These are the main reasons for the ongoing research programs toward GaN based-rectifiers on Silicon substrate for medium voltage range applications (600 V < Vbr < 1.2 kV)

Very low specific contact resistance measurements made on a highly p-type doped 4H-SiC layer selectively grown by vapor-liquid-solid transport

This work reports on the performances of ohmic contacts fabricated on highly p-type doped 4H-SiC epitaxial layer selectively grown by vapor-liquid-solid transport. Due to the very high doping level obtained, the contacts have an ohmic behavior even without any annealing process. Upon variation of annealing temperatures, it was shown that both 500 and 800 °C annealing temperature lead to a minimum value of the Specific Contact Resistance (SCR) down to 1.3×10−6 Ω⋅cm2. However, a large variation of the minimum SCR values has been observed (up to 4×10−4 Ω⋅cm2). Possible sources of this fluctuation have been also discussed in this paper

Influence of process parameters on electrical properties of PiN diodes fabricated with a highly p-type doped layer selectively grown by VLS transport

International audienceSiC Selective Epitaxial Growth (SEG) by Vapor-Liquid-Solid (VLS) transport on a bowl-shaped geometry appears to be a promising solution to perform deep, highly doped and high quality p-type doped area. Such SEG-VLS growth of highly p-doped (> 5x1019 cm-3) SiC layer was successfully demonstrated recently on large and small areas fabricated by Reactive Ion Etching (RIE). Moreover, a high quality P++(VLS)-N junction can be achieved by using this technique that offer new prospects for the achievement of new power electronics devices, including deeply buried peripheral protection zones such as guard-rings or JBS structures