Hot Carrier Trapping Induced Negative Photoconductance in InAs Nanowires toward Novel Nonvolatile Memory

摘要

We report a novel negative photoconductivity (NPC) mechanism in n-type indiumarsenide nanowires (NWs). Photoexcitation significantly suppresses theconductivity with a gain up to 10^5. The origin of NPC is attributed to thedepletion of conduction channels by light assisted hot electron trapping,supported by gate voltage threshold shift and wavelength dependentphotoconductance measurements. Scanning photocurrent microscopy excludes thepossibility that NPC originates from the NW/metal contacts and reveals acompeting positive photoconductivity. The conductivity recovery afterillumination substantially slows down at low temperature, indicating athermally activated detrapping mechanism. At 78 K, the spontaneous recovery ofthe conductance is completely quenched, resulting in a reversible memory devicewhich can be switched by light and gate voltage pulses. The novel NPC basedoptoelectronics may find exciting applications in photodetection andnonvolatile memory with low power consumption.