Since its discovery in 2004, graphene has been widely touted as a potential replacement for silicon in the next generation of electronic circuits owing to its exceptionally high carrier mobilities and its ultra-thin body. Graphene field effect transistors (GFETs) show promising potential for use in analog and radio frequency (RF) applications, with theoretically predicted THz frequencies only being limited by fabrication challenges. High series resistance of the source/drain access regions in a GFET is one such major factor responsible for performance degradation. In this thesis, a simple and straightforward scheme of reducing this resistance by self-aligned spin-on-doping of graphene using surface transfer dopants is presented. Back-gated GFETs were fabricated on Si/SiO2 and doped using various surface transfer dopants. A novel method of spin-on-doping graphene using poly(ethyleneimine) (PEI) was developed. Top-gated GFETs with mobilities up to 6,900 cm2/Vs were fabricated and their access regions were spin-on-doped in a self-aligned manner offering a 3X reduction in the series resistance. GFET drive currents improved by up to 4X and transconductances up to 3X after self-aligned doping. GFETs were also fabricated on insulating quartz substrates with mobilities up to 5,600 cm2/Vs and showed performance enhancements up to 2X after self-aligned doping. / text

Depuis quelques années, nous assistons à l’essor d’une nouvelle filière d’électronique basée sur des supports flexibles. De nombreuses applications difficilement atteignables par l’électronique classique sont visées, c’est notamment le cas des tags RFID, des capteurs mobiles, des écrans flexibles…. Cette électronique est essentiellement basée sur des matériaux organiques pour lesquels la faible mobilité (<1cm2 /V.s) limite considérablement les performances hyperfréquences des composants. Dans ce contexte, l’intégration hétérogène de composants des filières GaN et graphène sur substrat flexible apparait comme une solution prometteuse pour des applications de puissance hyperfréquence où la conformabilité sur surface non plane est souhaitée. Ces travaux présentent d’une part, une méthode de transfert de composants HEMTs AlGaN/GaN sur ruban flexible et d’autre part, une technique de manipulation du substrat souple et de fabrication directe des composants à base de graphène sur celui-ci. Des HEMTs AlGaN/GaN à faible longueur de grille (LG = 100nm) ont été transférés sur ruban flexible et ont permis d’atteindre des résultats à l’état de l’art en termes de puissance hyperfréquence avec un gain de puissance linéaire (Gp) de 15,8 dB, une densité de puissance de sortie (Pout) de 420 mW / mm et une puissance ajoutée (PAE) de 29,6%. Pour les composants à base de graphène, une technique de manipulation du substrat flexible a été développée et a permis de fiabiliser le procédé technologique de fabrication. Une fréquence de coupure ft de 1GHz et une fréquence maximale d’oscillation fmax de 3 GHz ont été obtenues. / In recent years, the field of flexible electronics has been expanding. Many applications difficult to achieve by conventional electronics are targeted as RFID tags, mobile sensors, flexible screens… This field is essentially based on organic material for which the poor mobility (<1cm2 /V.s) limits considerably the device performances. In this context, the heterogeneous integration of GaN and graphene devices on a flexible substrate appears to be a promising solution for microwave power applications where conformability on a non-planar surface is needed. This work presents, on the one hand, a method to transfer AlGaN/GaN HEMTs onto flexible tape and, on the other hand, a technique for handling and manufacturing graphene-based components directly on the flexible substrate. HEMTs with short-gate length (LG = 100 nm) have been transferred onto flexible tape and showed state of the art results in terms of microwave power with a linear power gain (Gp) of 15.8 dB, an output power density (Pout) of 420 mW/ mm and an added power efficiency (PAE) of 29.6%. Concerning graphene-based devices, a flexible substrate handling technique has been developed making the manufacturing process more reliable. A cut-off frequency ft of 1 GHz and a maximum oscillation frequency fmax of 3 GHz were obtained.