1. Poster Design & Printing by Genigraphics ® - 800.790.4001 Matlab-based Nanoscale Device Characterization Paul R. Haugen and Hassan Raza Nanoscale Devices and Systems Lab, University of Iowa www.engineering.uiowa.edu/~hraza INTRODUCTION METHODS AND MATERIALS CONCLUSIONS Usage RESULTS ABSTRACT CONTACT Hassan Raza, Assistant Professor Nanoscale Devices and Systems Lab University of Iowa hraza@engineering.uiowa.edu http://www.engineering.uiowa.edu/~hraza/ Device characterization is an extremely important aspect of any laboratory at any scale. As electronic devices are fabricated, whether it be using new materials, designs, or processes, accurate characterization of these devices is essential. In the interest of consistency, automation of the characterization process is essential. These devices are essential in areas of nanoelectronics, spintronics and energy harvesting technologies. In this context, the interfacings of laboratory characterization instruments with computers can be a difficult and resource intensive task. In this project, we present a package of automated software solutions to this problem for select laboratory instruments. It is intended to implement the capability to interface these instruments with a computer using Matlab and allow for automated characterization of both two and three terminal electronic devices. The data these applications generate can also be used to create plots that can be saved for later analysis. This software provides an effective and cost-efficient alternative to automating nanodevice characterization in an academic or industrial research laboratory. When the user starts the program, a number of choices are presented in a graphical user interface, each representing the capabilities of the software. Two terminal IV and CV and three terminal, three instrument output and transfer characteristics can be chosen. After selecting the application that is required, a graphical interface is displayed allowing the user to input the parameters necessary for their test. These can be the GPIB address of the instruments in use, starting or ending values of a voltage sweep, the increment or "step size" of the sweep, or any delay that the user would like to introduce for stabilization or other purposes. The application loops through the array of voltage points defined by the starting, ending, and step voltage values. The measured values are stored in an array and plotted against the array of voltage points created by the user. Should the user choose, these arrays along with a jpg image of the plot can be stored in a file. In this project, we use Matlab software to implement the device characterization automation. Matlab’s ability to easily manipulate the data produced and overall flexibility made it our choice. The interfacing technology used with this software is GPIB, which stands for General Purpose Interface Bus. GPIB is an interfacing technology developed by Hewlitt- Packard in the 1960's. It has a fairly high transfer rate (8mb/s), and a reliable and simple transfer protocol. We use Prologix USB-GPIB adapter to make the system usable by even a Laptop for overall mobility. The instruments that were used in this automation were three Keithley 236 IV meters, and one Keithley 590 CV meter. A DS360 Function Generator and SR830 Lock-in Amplifier from Stanford Research Systems were also used for conductance testing. In conclusion, this software provides that capability to perform reliable and accurate device characterization in laboratories with this equipment available. Compared to other options in automated device characterization, it is also the most affordable. The software required to run this application is about 10% of the cost of other typical automation software, and the costs of the interfacing hardware are under $500. There are many avenues for improvement in this software, and constant revisions and upgrades are being made, but even in its present form, this software presents the most practical way to automate device characterization in a laboratory environment. Consider a Carbon Nanotube transistor, Graphene transistor or a metal-oxide-silicon devices as shown below. To enable electrical characterization of these nanodevices, one needs a fully automated setup. With this combination of characterization and interfacing equipment, basic as well as advanced device characterization can be performed. For example, we show the three-terminal transfer characteristics of a Carbon Nanotube transistor, where the current through the carbon nanotube is modulated as a function of the back gate voltage as well as top gate voltage. The device performance shows that the top gate has a much better control on the ON/OFF characteristics of the device compared to the back gate voltage. Such insight in the device performance is not possible without the automated characterization software described here. In this manner, two- or three-terminal IV characterization can be done with the Keithley 236 SMUs. Capacitance vs Voltage can also be measured using the Keithley 590. For the AC characterization, one may use lock-in amplifier technique (SRS SR830) and spectrum analyzer (SRS SR780). Graphical User Interface CNT Transistor Characterization Carbon Nanotube Transistor Graphene Transistor Metal Oxide Silicon