Record Negative Photoconductivity in N‐Polar AlGaN/GaN Quantum‐Well Heterostructures

The AlGaN/GaN quantum‐well heterostructures typically exhibit a positive photoconductivity (PPC) during the light illumination. Surprisingly, the introducing the GaN/AlN superlattice (SL) back barrier into N‐polar AlGaN/GaN quantum‐well heterostructures induces a transition in these heterostructures from PPC to negative photoconductivity (NPC) as the SL period number increases at room temperature. This transition occurs under an infrared light illumination and can be well explained in terms of the excitation of hot electrons from the 2D electron gas and subsequent trapping them in a SL structure. The NPC effect observed in N‐polar AlGaN/GaN heterostructures with SL back barrier exhibits photoconductivity yield exceeding 85 and thus is the largest ones reported so far for semiconductors. In addition, the NPC signal remains relatively stable at high temperatures up to 400 K. The obtained results can be interesting for the development of NPC related devices such as photoelectric logic gates, photoelectronic memory, and infrared photodetectors.