Low-Cost Embedded Instrumentation for Automated Semiconductor Diode Characterization

Current-voltage characteristics of semiconductor devices provide important information about their electrical behavior which are critical to accomplish accurate device modeling and simulation of circuits containing such devices. Tracing the current-voltage (I-V) curves of semiconductor devices is an important measurement that is essential for education and training in semiconductors, circuit design, research and development, and industry applications. The cost of commercial I-V curve tracers often pose a barrier to semiconductor education and research, especially in developing regions, K-12 schools, and small-scale research labs with limited resources. In this paper, we present a low-cost solution using a mixed-signal Programmable System-on-Chip (PSoC) to characterize the I-V curve of a diode. By effectively utilizing the onboard analog and digital components of the PSoC, such as operational amplifiers, voltage digital to analog converter (VDAC), analog multiplexer, and analog to digital converter (ADC), we have designed an instrumentation hardware system that facilitates fast, reliable and reproducible measurement of a diode's I-V curve. A custom-built graphical user interface (GUI) program was developed in python which allow users to easily interact with the hardware system to perform automated experiments, acquire and plot data, and automatically analyze the data to extract important diode parameters such as the reverse saturation current and the ideality factor. Our single-chip instrumentation system can characterize a diode with an upper limit of drive current of ∼80mA. With only a cost of ~$20 USD, our PSoC-based embedded instrumentation performs accurate diode testing and promises to democratize the access to an affordable semiconductor device characterization system.