Nanoelectronics Research Lab

 

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Notice: Information on this page is outdated and needs to be revised, please check our publications section to have an idea of the research topic we are currently working on.

Growth of Germanium, Silicon Nanowires and Core-Shell Heterostructures

 

Semiconductor nanowires offer a natural, quasi-one dimensional test-bed for electron physics in reduced dimensions and as a platform for electronic devices. Core-shell nanowires represent the quasi one-dimensional counterpart to the two-dimensional quantum well. We are exploring the growth of band- and strain-engineered Ge-SiGe and Si-SiGe core-shell nanowires in order to tailor the structure’s electronic properties. We have also grown modulation doped Ge-SiGe nanowires as a method to enhance the carrier mobility of this system.

fig1aTEMRender_13

(Electron microscope images of core-shell nanowires and cut-away schematic of modulation doped core-shell nanowire)

High Performance Nanowire Field-effect and Tunneling Field-effect Transistors

 

Owing to CMOS scaling issues, and in particular to increased power dissipation in aggressively scaled transistors, there is significant interest in devices that provide a lower dissipated power at the same switching speed. Gate-all-around nanowire field-effect transistors and tunneling field-effect are two device designs that can provide a reduced operating power, thanks to better electrostatic control of the channel.

We are investigating the fabrication and the electronic properties of germanium gate-all-around nanowire field-effect transistors, tunneling field-effect transistors and modulation doped field-effect transistors. The devices are realized using Ge-SiGe or Si-SiGe nanowire heterostructures and highly doped source and drain for efficient electron injection. Modulation doped nanowire FETs show enhanced low-temperature hole mobility and decoupled transport through core and shell regions over undoped structures.

 

      

 

(Ge-SiGe p-type modulation doped Field-Effect Transistor)

 

 

TFET   SEM

 

(Ge-SiGe p-i-n Tunneling Field-Effect transistor)

Electronic Transport in Graphene Bilayers

 

When two layers of electrons are brought in close proximity, new phenomena with no counterpart in the physics of the single layer can emerge. A most notable example is the electron-hole pairing and exciton condensation which occurs at low temperatures in two closely coupled quantum wells. Using transport techniques such as Coulomb drag and interlayer tunneling, we are exploring electron-electron correlations and quantum coherence in two graphene layers separated by an ultra thin dielectric.

 

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Last update 12/1/2015