Imperfection in Semiconductors Leading to High Performance Devices.

Semiconductors form the basis of high-performance optoelectronic devices, enabling efficient light emission and detection. While crystalline perfection is generally sought to optimize device performance, specific lattice defects can endow materials with unexpected and useful functionalities. Here, we show that engineered defect states in gallium nitride (GaN) diodes markedly enhance their response to high-energy protons. Through a combination of device simulations and experimental measurements, we demonstrate that forward biasing the diode just below its turn-on voltage activates a defect-mediated photoconductive regime. This operating mode induces substantial carrier trapping and photoconductive gain while simultaneously suppressing the dark current-a behaviour in stark contrast to conventional photoconductors. The exploitation of this previously underexplored detection mechanism yields a three-orders-of-magnitude enhancement in sensitivity over standard photovoltaic operation, enabling reliable quantification of proton fluxes down to a few particles per second. This novel mode of operation is not limited to protons but also extends to X-rays and other high-energy particles, and may be generalized to a broader class of semiconductors exhibiting high levels of doping compensation. These findings open new avenues for very low-flux particle detection across diverse application spaces, including medical, astronomy, and industrial imaging.