Influence of N incorporation on persistent photoconductivity in GaAsN alloys

Colossal X‐Ray‐Induced Persistent Photoconductivity in Current‐Perpendicular‐to‐Plane Ferroelectric/Semiconductor Junctions

“…Such a significant reduction of φ b by 0.3–0.4 eV is responsible for the huge enhancement of conductivity from the pristine state to the PPC state. This mechanism intrinsically differs from that proposed previously for current‐in‐plane heterostructures, in which the enhancement of carrier density or mobility was the dominant factor.…”

“…For example, in bulk semiconductors or thick films, the microscopic barriers at the atomic level originate from defect‐related traps as reported for SrTiO 3 , VO 2 , and BiFeO 3 , or from random composition variations as reported for Zn 0.3 Cd 0.7 Se . In semiconductors like GaAs alloys and ZnO films, PPC was proposed to be related to DX centers which are deep‐level traps undergoing lattice distortion after photon excitation . For planar semiconductor heterostructures (Figure b), such as n‐GaAs/p‐GaAs, and LaAlO 3 /SrTiO 3 , a macroscopic junction barrier is believed to spatially separate the photoexcited electron/hole pairs in the in‐plane transport and thus account for the PPC effect …”

“…Persistent photoconductivity (PPC), i.e., electromagnetic radiation induced conduction that can persist for a long time after the termination of illumination, has potential applications in areas such as bistable optical switches, holographic memories, and bioelectronics . While most of the works on PPC were carried out with visible and UV light, X‐ray‐induced PPC (XPPC) has also been observed in a number of different materials including manganites, AlGaAs semiconductors, and VO 2 films . Regardless of the illumination sources, basic features of PPC include the slow relaxation of the conductivity after the termination of photon excitation and the efficient recovery of the pristine insulating state through thermal annealing .…”

“…Regardless of the illumination sources, basic features of PPC include the slow relaxation of the conductivity after the termination of photon excitation and the efficient recovery of the pristine insulating state through thermal annealing . In terms of materials and device configurations, the investigations on PPC in recent decades have mainly focused on semiconductor bulks or films ( Figure a) and their planar heterostructures, where the current flows in the plane of the film (Figure b). The key mechanism of PPC in these systems is that the microscopic energy barriers suppress the recombination of electrons and holes once they are photoexcited.…”

“…A common feature of these PPC structures is that the electric transport was measured in plane, and the PPC effect is limited by the modulation of the photon‐sensitive layers themselves. The magnitude of the reported PPC effect is moderate because of the limited carrier density/mobility ( n /μ) modulation of the active materials . The energy barriers suppress the recombination of photoexcited electron/hole pairs, which, however, do not contribute directly to the in‐plane enhanced conductivity.…”