Recently, Professor Min Qiu’s research group reported a breakthrough in semiconductor optoelectronics. The work of Xiaoguo Fang, a PhD candidate admitted in 2020, titled ”Geometrical Tailoring of Shockley–Ramo Bipolar Photocurrent in Self-powered GaAs Nanodevices“，has been accepted by Advanced Optical Materials.

The study demonstrates zero-bias Shockley–Ramo (SR) bipolar photocurrent in GaAs nanoconstriction channels, with programmable control via device geometry, optical power, and temperature. The team shows that nanoscale geometric confinement reshapes carrier diffusion, while power-dependent Γ→L intervalley scattering in GaAs reversibly tunes electron–hole asymmetry. As a result, a single device achieves polarity switching and amplitude tuning of the photocurrent.

Spatially resolved scanning photocurrent measurements, multi-wavelength and temperature controls, and modeling confirm that the response is governed by the SR weighting field and carrier diffusion, and is clearly distinct from photothermoelectric (PTE) effects. The experimental data agree closely with the SR–diffusion model established by the authors.

This work provides a practical pathway toward bias-free, low-power optical logic, neuromorphic sensing, and high-contrast imaging, and extends the application scope of conventional semiconductors in programmable photodetection.

Paper Link：https://advanced.onlinelibrary.wiley.com/doi/10.1002/adom.202501597