Gleaning new information from an old experiment
By simply illuminating samples with light of known intensity, researchers can extract valuable additional information on semiconductors while performing a measurement developed 140 years ago.
Named after Edwin Hall, the Hall effect was discovered in 1879. By measuring the voltage generated across a sample when a magnetic field is applied at right angles to a current flowing along its length, physicists can find out the density of the main charge carriers and how fast they are travelling. But they have to use other techniques to ascertain information about other charge carriers that make a small contribution to the total current.
Now, a KAIST-led team has shown that, by shining light on a sample while making the measurement, they can measure up to seven parameters, which includes information about minority carriers. This promises to greatly simplify measurements on semiconductors, helping to accelerate the development of solar cells and optoelectronic devices.
- Nature 575, 151–155 (2019). doi: 10.1038/s41586-019-1632-2