Abstracts Category : Other

AlGaSb/InAs vertical tunnel field effect transistors for low power electronics : Transistors effet tunnel vertical htrojonction AlGaSb/InAs pour lectronique basse consommation

by Vinay Kumar Chinni

Depuis une dizaine dannes, la miniaturisation des circuits microlectroniques silicium est freine par laugmentation de la densit de puissance consomme car la rduction de la tension dalimentation na pas suivi celle des dimensions. Cela est inhrent au mcanisme thermo-ionique dinjection des porteurs dans les transistors de type MOSFET et conduit envisager un mcanisme dinjection des porteurs diffrent, bas sur leffet tunnel. Pour tre efficace, cette solution doit saccompagner de lintroduction de semi-conducteurs III-V faible masse effective et petite bande interdite. Parmi ces derniers, lhtrojonction (Al)GaSb/InAs semble prometteuse grce la possibilit de passer dun alignement des bandes de type "chelon" "bris". Ce travail de thse porte sur la fabrication de transistors effet tunnel (TFET) base dhterostructures (Al)GaSb/InAs. Linfluence des paramtres matriaux et gomtriques sur les performances du transistor a t value laide des simulations utilisant le logiciel Silvaco. Le dveloppement dun procd technologique complet de fabrication de diodes et transistors verticaux de taille nanomtrique a ensuite permis la ralisation dun TFET sur substrat GaAs. Sa caractrisation lectrique a rvl un courant dans ltat ON de 433 A/m VDS = VGS = 0.5 V. A basse temprature, une pente sous le seuil de 71 mV/dcade et un rapport ON/OFF de 6 dcades ont t obtenus. Ce compromis ltat de lart entre courant ON et capacit de commutation dmontre que le TFET base de lhtrojonction (Al)GaSb/InAs pourrait constituer une alternative de choix pour les technologies futures aprs optimisation de lempilement de grille. Silicon microelectronics is facing a power consumption crisis for around ten years since the scaling of the supply voltage has not followed that of the transistor dimensions. This is mainly due to the inherent limits of the silicon MOSFETs, based on the thermionic injection mechanism of the carriers. Going to a tunneling injection mechanism is therefore very appealing but, to be efficient, this should go along with the introduction of low effective mass and small bang gap III-V semiconductors. Among them, the (Al)GaSb/InAs heterojunction is very attractive due to the ability to tune the band alignment from staggered to broken gap which eventually results in large tunneling current densities. In this PhD work, the fabrication of tunnel field effect transistors (TFETs) based on AlGaSb/InAs heterostructures grown by molecular beam epitaxy is investigated. First the impact of the basic material and geometrical parameters on the device performances has been simulated using Silvaco TCAD software. A complete technological process for the fabrication of nanoscale vertical tunnel diodes and tunneling transistors has then been developed and has led to the achievement of a vertical TFET on a GaAs substrate. The electrical characterization of this device has been carried out exhibiting an ON-current of 433 A/m at VDS = VGS = 0.5 V. At low temperature, a subthresholdAdvisors/Committee Members: Wallart, Xavier (thesis director), Zaknoune, Mohammed (thesis director), Desplanque, Ludovic (thesis director).