Single vertical InP nanowire diodes with low ideality factors contacted in-array for high-resolution optoelectronics.

Abstract

Nanowire (NW) optoelectronic and electrical devices offer unique advantages over bulk materials but are generally made by contacting entire NW arrays in parallel. In contrast, ultra-high-resolution displays and photodetectors require electrical connections to individual NWs inside an array. Here, we demonstrate a scheme for fabricating such single NW vertical devices by contacting individual NWs within a dense NW array. We contrast benzocyclobutene and SiO2 planarization methods for these devices and find that the latter leads to dramatically improved processing yield as well as higher-quality diodes. Further, we find that replacing the metal top contact with transparent indium tin oxide does not decrease electrical performance, allowing for transparent top contacts. We improve the ideality factor of the devices from a previous n = 14 to n = 1.8, with the best devices as low as n = 1.5. The devices are characterized as both photodetectors with detectivities up to 2.45 AW^-1and photocurrent densities of up to 185 mAcm^-2under 0.76 suns illumination. Despite poor performance as light emitting diodes, the devices show great resilience to current densities up to 4×108 mAcm^-2. In combination with growth optimization, the flexibility of the processing allows for use of these devices as ultra-high-resolution photodetectors and displays.