The Electroluminescent Devices Automated Characterization System
The current method used for characterization of electroluminescent (EL) devices can take up
to eight hours to complete. Furthermore, the lab assistant performing the
characterization can make mistakes that will lead to erroneous measurements and
conclusions. Due to the time constraint involved, the number of measurements
that can be taken is severely limited.
The Electronic Device Laboratory of The University of Texas at
El Paso, under the supervision of Dr. Gregory Lush, sponsored the
Electroluminescent Devices Automated Characterization System (ELDACS).
Based on the main issue of time, an automated process for characterization was implemented;
one that allows the researcher to free up valuable time while also giving more reliable and
numerous measurements. ELDACS conducts the necessary measurements to automatically characterize an EL
sample (8 EL devices) once initiated and then store that data for a lab assistant
to view later. Test runs of the systems have resulted in a total running time of approximately
two hours and ten minutes, which is a drastic reduction from the six hours it would take for a lab
Method of Completion
Using a combination of software developed in the LabVIEW programming
environment, interfaces with hardware using data-acquisition (DAQ) and general
purpose interface bus (GPIB) cards, and mechanical motors and electrical circuits,
a well-integrated system will be developed that can operate independently of outside
input after initial setup.
The software will control the flow of the process, the interfaces will link the software
with the hardware, and the hardware will perform the required tasks. Each section will be
designed and developed by a competent and experienced electrical engineering student.
Each student will also be responsible for the integration of their assigned section into the
overall scheme. This division of work will ensure the project will be completed within
the prescribed time frame of August 26, 2001 to May 3, 2002.
This block diagram shows the interconnection of the components, the signal flow
and the control flow. Different colors indicate the different responsibilities.
ELDACS was incorporated into the previously existing characterization system.
This situation allowed for a reduced cost of supplies but also came with a drawback. As most
of the equipment was already purchased, this meant that ELDACS had to be built specifically for
This is the stepper motor circuit used to control and drive the stepper motors in the
X and Z directions
This is the enclosure that houses all the circuits which provide the connection between the
old and new characterization systems. The topmost circuit contains the hardware interface that allows the user
to manually select devices if the system is in manual mode or to override the automated run if something is wrong
This is the XYZ table that holds the sample along with the motors that align each device with the
spectrometer. The enclosure around the table allows the process to run while the lights in the room are on
This plot shows the correlation between the old intensity measurements (denoted by Minolta) and
the new measurements (Slit 0.25-1.5). The conversion factor between the old measurements and those found using
a slit opening of 0.25mm is 10,350. This will allow for the comparison of older data with that of the new system.