Building transistors with semiconductors other than silicon is a key focus for the electronics research community — and the pages of Nature Electronics. This issue, for instance, features devices based on two-dimensional semiconductors and on organic semiconductors, and last month it was devices based on perovskite semiconductors1. The use of these emerging materials can, however, create challenges when it comes to assessing and reporting performance.

One such area is Hall effect measurements. These measurements can be used to determine the charge carrier density and mobility of semiconductors, and can help distinguish different transport mechanisms. They are also increasingly used to determine the electronic properties of emerging semiconductor materials. But they do need to be performed — and reported — carefully. Measurements with the materials can be susceptible to artefacts and the interpretation of results complicated by factors such as hopping contamination and mobile ions.

In a Comment article in this issue, Vladimir Bruevich and Vitaly Podzorov highlight the need for rigour and clarity in the reporting of Hall effect measurements. Notably, the researchers — who are based at Rutgers University — provide a checklist to assist researchers when performing such measurements, as well as to assist reviewers when assessing these measurements.

The checklist covers eight key areas: varying the magnetic field and longitudinal excitation current; linearity of the Hall voltage with the magnetic field and excitation current; four-probe conductivity measurements; switching between contacts in the Van der Pauw configuration; long-term evolution and hysteresis of the Hall signal; apparent frequency dependence in a.c. Hall measurements; including raw Hall data in publications; and description of studied devices.

To illustrate the need for care when using Hall effect measurements — and the potential need for the checklist — Bruevich and Podzorov analysed papers published over the last 20 years that reported Hall mobility measurements for certain emerging semiconductor materials: namely, perovskites, conjugated polymers and crystalline small-molecule organic semiconductors. They give each article a score (a Hall reliability score) from 0 to 16 based on the number of points from the checklist that the work addresses.

In general, the papers examined have relatively low scores on this scale over the years. And for perovskite-based systems — which includes metal oxide, chalcogenide and halide perovskites — the average Hall reliability score was found to have declined over the years. (During the same period, the average reported mobility was found to have gone up.)

Careful benchmarking is also important for the development of devices based on emerging semiconductors. Back in 2022, Zhihui Cheng, Aaron Franklin, Curt Richter and colleagues proposed guidelines for the reporting and benchmarking of field-effect transistors based on such materials2. Their analysis included a checklist of device parameters to report, as well as a series of recommended benchmarking plots to evaluate device performance against other transistors.

These are valuable steps in improving the assessment, reporting and benchmarking of devices based on emerging semiconductor materials. But work remains to be done in the community, and at the journal3. Nevertheless, it is worth remembering that these issues have arisen, in part, due to one of the strengths of the field — it is a field driven by the collective efforts of researchers from a broad range of disciplines, including chemists, physicists, materials scientists and electrical engineers.