Facilities

Facilities:

Low Temperature Scanning Probe Microscope

Our LT-STM/QPLus AFM (Scienta Omicron) is composed of an atomically sharp scanning probe tip, typically made from chemically etched tungsten wire. The probe tip is attached to a piezo drive and a coarse positioning motor which are used to scan across a sample surface with the ability to measure the topography and the local density of states on the atomic scale. The whole assembly is housed in an ultra-high vacuum (UHV) chamber with base pressure <10^-10 mbar. The sample and tip can be cooled, via the cryochamber, to <5K for >65h. For STM/S the tunneling current, topography and local density of states are measured by applying a bias voltage between the tip-sample junction. For QPlus AFM, the AFM tip can achieve atomic resolution and can be functionalized to measure electronic bonds in molecules (https://science.sciencemag.org/content/340/6139/1434/tab-pdf ) Achieving atomic resolution requires serious considerations for vibration isolation and sample preparation. To that end the STM stage assembly is equipped with suspension springs and an eddy current dampening system. Additionally, the STM, growth chambers, and table rest on pneumatic table legs designed to reduce vibration. We are implementing different light sources for in-operando measurements and we have various evaporators and ion-guns in an attached preparation chamber for thin film growth and sample preparation.

Pulsed Laser Deposition Setup

Pulsed laser deposition(PLD) is a deposition technique for depositing high quality crystalline thin films onto substrates in high vacuum. The films generally match the stoichiometry of the targets and have a controllable thickness based on deposition time and other parameters [Chem. Soc. Rev. 2004, 33, 23]. Our PLD system uses an excimer gas laser at 248 nm wavelength. The laser is focused toward a target with a series of lens through a special window into a high vacuum chamber. The beam hits the target at high pulse rate and high intensity and once the laser light is absorbed electrical excitation energy is converted into thermal energy thereby creating a plasma plume[Chem. Soc. Rev. 2004, 33, 23]. An image of one of the plumes can be seen in figure. The thermal energy results in evaporation of atoms, molecules, and ions which make up the plasma plume. This process of absorption and evaporation is known as laser ablation[Chem. Soc. Rev. 2004, 33, 23]. The aforementioned plasma plume is directed towards the substrate where the materials lay down on the surface. After some time a film of increasing thickness forms. Our deposition chamber is equipped with various leak valves and can hold 6 ablation targets at a time. The sample holder has a wide temperature range for heating. Sample quality is checked with a low energy electron diffraction (LEED) gun in an attached chamber. The whole assembly is attached via a load lock to the LT-STM chamber.

Programmable Dip Coater

The SMSG has expertise in successive ionic layer adsorption and reaction (SILAR) growth methods and implements a programmable dip coater for precise control over growth and deposition parameters of nanomaterials. We also use the dip coater for thin film coating of organic and inorganic materials on different substrates and meso-structures. Our DiP coater is located in the Cowboy Microfabrication Corral of the Physical Science building.

Programmable Spin Coater

We have a programmable spin coater for thin film deposition. Our spin coater is housed inside a double glove box in the Cowboy Microfabrication Corral in the Physical Science building

Tube Furnace

We use a tube furnace for various crystal growth methods and have plans to transform our standard tube furnace into a sliding tube furnace with controlled temperature and chemical vapor deposition capabilities. Stay tuned....

Fume Hood

Our fume hood is equipped with a complete Schlenk line setup for different chemical synthesis procedures. Additionally we have stirring hot plates, and assorted glass ware.