Extensive material characterization efforts are carried out at CSU’s NGPV in collaboration with CSU’s Central Instrumentation Facility and Loughborough University in UK to understand the effects of varying process parameters. Greater understanding of material behavior at microscopic level enables researchers at NGPV to optimize the process condition to get to efficiency goals.

Scanning Electron Microscope (SEM)

SEM is a very important tool to understand the surface topography of the deposited sample. It gives important information about the coverage of the film, its uniformity, consistance, etc. Energy Dispersive X-ray Spectroscopy along with SEM may be used to get chemical map and distribution over the surface of the sample.

FIB Dual Beam for TEM sample preparation

Focused Ion Beam is used to prepare thin cross section samples for imaging and chemical analysis to be used with Transmission Electron Microscopes. NGPV’s collaboration with CREST (Center for Renewable Energy Systems Technology) at Loughborough University has empowered researchers to take understanding of material science of thin films to the next level. TEM samples less than 100 nm thin are prepared using FIB Dual Beam for use with TEM.

Using Electron Back Scatter Diffraction Spectroscopy (EBSD) has made it possible to visually understand the growth orientation of grains as film is deposited during closed spaced sublimation process. Twin boundaries are distinctly detected using this method.

Transmission Electron Microscope (TEM)

Transmission Electron Microscope is extensively used to study CdTe films deposited at NGPV to understand material behavior at microscopic level. High Resolution Transmission Electron Microscopy enables researchers to very precisely image film properties like grain size, stacking faults, grain boundaries, etc.

Energy Dispersive X-ray Spectroscopy (EDS or EDAX) 

EDS or EDAX used along with TEM is a very powerful tool that maybe used to understand chemical profile of films and as they change with change in process and treatment parameters.

X-ray Photoelectron Spectroscopy (XPS)

X-ray Photoelectron Spectroscopy is a surface sensitive technique. It is also a useful tool to understand the distribution of material as a function of film depth. The film can be sputter etched layer by layer to achieve detailed information like presence of elements and their stoichiometry.