Observation of “Negative” Persistent Photoconductivity Effectat T > 200 °C in N‐Polar GaN/AlGaN/GaN Heterostructures

It is rarely reported that semiconductor materials can exhibit the “negative” persistent photoconductivity (PC) effect. In this work, the “negative” persistent PC effect was observed in the nitrogen (N)‐polar oriented GaN/AlGaN/GaN heterostructure under the sub‐bandgap illumination (2.0–2.8 eV) in the temperature range of 200–250 °C. This is the first observation of the negative persistent PC effect in semiconductor materials at such high temperatures. The phenomenon was explained based on the model, which assumes the interaction between the absorbed oxygen species on the N‐polar GaN surface, the DX centers in the GaN channel layer, and the two‐dimensional electron gas at the GaN/AlGaN interface. The discovery of high‐temperature “negative” persistent PC in N‐polar III‐nitride heterostructures may lead to novel applications such as temperature‐stable optical memories. Furthermore, the results presented here, together with our recent observation of record negative PC [Advanced Photonics Research (2025), p. 2500130], reveal new physics in N‐polar nitride heterostructures.