Science and Technology Facility
Solar cell, thin film, and nanostructure research are conducted in our Science and Technology Facility (S&TF) with the benefits of a forty percent reduction in energy use compared to standard laboratory buildings; energy recovery for ventilation in laboratories; and functional and flexible laboratory space.
Designed specifically to reduce time delays associated with transferring technology to industry, the S&TF's 71,000 square feet is a multi-level facility of laboratory space, office space, and lobby connected by an elevated bridge to the Solar Energy Research Facility (SERF). The S&TF houses the Process Development and Integration Laboratory (PDIL) and nine advanced material synthesis, characterization, and general support laboratories.
Process Development and Integration Laboratory
Located in the center of the S&TF is the Process Development and Integration Laboratory (PDIL) with 10,170 square feet of laboratory space dedicated to a new class of thin-film photovoltaics (PV) deposition, processing, and characterization tools. One of the exciting capabilities in the PDIL is the ability of researchers to pass samples between equipment without contamination from the air. The integrity of this process is possible through the Process Integration Project. Other capabilities of the PDIL include a thorough integration of control systems and databases enabling researchers with various expertise to work together using integrated tools and integrated data. An added advantage is having scientists collaborate in a facility that is easily accessible with no physical separations.
Interconnect Process Development Laboratory
Research in thin-film PV will be accomplished in this lab with techniques used for monolithic integration of cells into modules. Developing ways to make small, thin-film modules onsite will be useful in demonstration purposes. Defining the best ways to use laser and mechanical scribing to make monolithically integrated modules, as well as depositing insulators by spray deposition of nano-particles will help close the gap between cell and module performance for thin-film PV.
PV Manufacturing Diagnostics Laboratory
Equipment dedicated to the study of PV materials and devices including optical diagnostics, PVScan, etc., will be available in this lab.
User Characterization Laboratory
Three associate labs all designated under the User Characterization Laboratory include work in Sample Preparation, General Equipment, and Specialized Equipment:
Equipment for final device electrical contacting and isolation steps performed prior to light/dark current-voltage and spectral quantum efficiency measurement will be housed in this lab. This lab is physically separated from the other User Characterization Labs because of its chemical and process capabilities used in these contact and isolation steps.
Routine Analysis and quality control will be conducted at this lab with equipment such as stylus profilometry and ellipsometry for thickness measurement, and optical microscope for routine surface morphology analysis. Most of this equipment will be used for training and by a variety of users.
With more specialized apparatus including a Hall and four-point-probe for electrical analysis, and UV-Vis.-NIR spectrophotometers for optical analysis, the equipment in this laboratory complements the equipment in the Sample Preparation Lab. Most equipment in the Specialized Equipment Lab is more complex and operated by a limited user base.
Electro-Optical Diagnostic Development Laboratory
In this lab, researchers will collaborate with other research teams in using established in-situ electro-optical characterization techniques to develop new in-situ diagnostics tailored for the specific growth and processing steps used in PV manufacturing. Spectroscopic ellipsometry, photoluminescence, photocurrent decay, reflectometry, fourier transform infrared, and Ramen scattering are experimental techniques that will be used to develop new diagnostic tools directly applicable in manufacturing.
Surface Analysis Laboratory
This lab will study and control PV surfaces and interfaces. High spatial resolution Auger electron spectroscopy (AES) will provide essential complementary information on the elemental makeup and distribution in PV films. The XPS/UPS system will enable data collection on insulating samples, the probing of both core level and valence band electronic structures, and will provide information on the chemical environments of specific elements. These capabilities will ultimately provide a platform for the study of in-situ real-time control of PV device manufacture.
Analytical Microscopy Laboratory
This lab will study PV surface and interface morphologies that are of interest to the PV community. Scanning probe microscopies and scanning electron microscopy (SEM) will be used to provide real space characterization of PV material morphologies and electronic structures down to the nanometer scale.
Thin-Film Deposition/Process Development Laboratory
As the second largest laboratory in the S&TF, this lab will support the work of three different material types:
Deposition Techniques to deposit various semiconductor layers necessary to form the active junction regions of polycrystalline II-VI devices are conducted in this area of the lab. Deposition processes include close-spaced Sublimation (CSS), sputtering, and evaporation. Materials include CdS and CdTe, as well as related ternary and quaternary alloys such as CdZnTe, CdSTe, and CdZnSTe. Equipment used to modify properties of deposited films, such as heat-treatment using CdC12 vapors; development activities related to in-situ process monitoring; and equipment required for substrate cleaning will be resources in this lab.
Development of absorber, window, and metal contact thin film layers for Cu(In,Ga)Se2-based photovoltaic devices are performed in this area of the lab. Thin-film layers will be deposited by physical vapor deposition methods and other hybrid methods to integrate improved deposition techniques, critical issues related to the surfaces/interfaces between layers, and in-situ control and diagnostics. Higher performing solar cells and improved deposition methods for industrial processes are expected outcomes in this lab.
Study of Amorphous and thin silicon materials and devices will be performed in the third area of the lab. This includes electo-optical and thermal processing capabilities. The area is built to accommodate deposition processes in the future.
Contact Process Development Laboratory
In this laboratory, various surface modification and deposition processes will be used to develop materials and investigate function of various front and back contact schemes for advanced thin-film photovoltaic solar cells. Contact materials include metals, semiconductors, and transparent-conducting oxides (TCOs). Surface modification processes include semi-automated chemical cleaning for ceramic substrates in a micro-clean environment, as well as in-situ plasma etching (PE) and reactive ion etching (RIE) within vacuum chambers prior to material deposition. Deposition processes include resistive and electron-beam evaporation, d.c. and r.f. sputtering, molecular-beam epitaxy (MBE), and chemical-vapor deposition (CVD). In-situ surface characterization is used on some equipment including a Kelvin Probe for analysis, and residual-gas analysis (RGA) for information regarding incorporation of trace impurities from the sputtering environment into contact materials.
Wet Chemistry/Electrodeposition Process Development Laboratory
Chemical (wet) processes will be used to deposit metal, oxide, and semiconductor thin-films for existing programs, as well as research aimed at development of novel processes and materials for next-generation technologies. Routine chemical depositions include CdS and related alloys for use in CdTe and CIGS polycrystalline device technologies. The lab will include apparatus for post-deposition thermal treatment, and equipment to perform inductively coupled plasma spectroscopy (ICP) required for elemental compositional analysis of bulk and trace impurities.