ReAGaN

Telecom infrastructures are based on various standards using different modulation schemes (PSK, QPSK…..) characterized by a Peak to Average signal Ratio (PAR) which can reach 10.5dB for W-CDMA modulation. The expected 4G standards (Evolved UMTS and WiMax) are operating OFDM multiplexing technology which presents the advantage to be robust but leads to increase the PAR in parallel. Combining stronger electric performances requirement (linearity and RF power) and the economical constraint of the zero defect, it is evident that the reliability of power amplifier appears to be a crucial aspect. UMS, main industrial actor in the field of microwave electronic components and circuits, intends to industrialize GaN based power component covering such telecom applications. Wide band gap technologies represent the corner stone for the next generation of telecommunication systems and such development is critical to maintain independence and industrial competitiveness in Europe. The technological process maturity is a key factor to reach reliability requirement. This explains why the purpose of this project is the development of a specific and dedicated methodology for characterization and physical analysis of GaN technologies. The ReaGaN project clearly aims at supporting the industrialization of GaN technologies. This requires a deeper understanding of the physical mechanisms taking place in GaN devices as well as the investigation of material properties and their evolution during the process as they determines the resulting performances of the amplifier. To reach this end, new analysis techniques dedicated to Wide Band Gap semiconductor technologies have still to be improved or developed. These analytical techniques include electrical diagnostics as well as physical and structural characterization techniques. In particular, it is expected that the correlation of the results given by electrical and physical techniques proposed and used in this project will lead to the identification, characterisation and localization of nano-structural defects and physical mechanisms taking place in GaN technologies and potentially responsible for degradation. During this project, devices issued from the evaluation and qualification of UMS processes will be analyzed in significant details. UMS is currently developing two GaN technologies built on SiC substrate for high thermal properties: Power bar GH50, and Monolithic Microwave Integrated Circuit (MMIC) GH25 technologies based on 0.5µm and 0.25µm gate length transistor respectively. During this project, specific devices or structures will be procured to the consortium partners to investigate particular processing options of the technology (eg gate module, passivation, epistructure …). The life tests of the devices will be performed in the frame of UMS internal projects. The comparative analysis of different processing steps will provide important and pertinent information to support the step-up of the GH25 and GH50 technologies from one generation to the next one. The complementarities between techniques will be demonstrated as a proof of the existing interaction between electrical transport properties, light characteristic and material structural properties. This project involves three academic partners (IMS UMR CNRS, LAAS UPR CNRS, LEPMI UMR CNRS) and three companies (UMS, TRT, SERMA). The project duration isof three years.