Use of the SM7110 to Evaluate I-V Characteristics of Photodiodes in Optical Communications

This application note proposes a method for evaluating the I-V characteristics of photodiodes and avalanche photodiodes using synchronized measurement of minuscule currents while a DC voltage is varied.

Market trends

The volume of data handled in wireless communications is forecasted to grow due to growing adoption of next-generation communications standards such as 5G as well as inter-vehicle communications like vehicle-to-everything (V2X), remote medicine, and other technologies. Signal transmission using cables is subject to concerns of loss and delay times when sending large amounts of data at high speeds. Optical communications using semiconductors with optical characteristics known as photodiodes (PDs) and avalanche photodiodes (APDs) are attracting attention as one solution to those concerns.


It’s typical to use a DC voltage source and a microammeter to measure I-V characteristics, a key electrical characteristic in evaluating PDs and APDs. However, using these two devices can get to be cumbersome. Not only can it quickly become tiresome, accuracy can suffer from the increase in noise due the complicated wiring between the two devices.


The Super Megohmmeter SM7110 consists of a DC power supply that can apply a DC voltage within the broad range of 0.1 V to 1000 V and a microammeter with a minimum range of 20 pA (resolution: 0.1 fA). As a result, the instrument can perform synchronized measurement of minuscule currents while applying a large range of DC voltage. Furthermore, the SM7000 Series Sample Application (for the SM7110, SM7120, and SM7420), makes it easy to generate graphs of measurement results (free download from Hioki's website). 

Measurement data

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