title: GaP-ZnS pseudobinary alloy nanowires.
abstract: Multicomponent nanowires (NWs) are of great interest for integrated nanoscale optoelectronic devices owing to their widely tunable band gaps. In this study, we synthesize a series of (GaP)(1-x)(ZnS)(x) (0 ≤ x ≤ 1) pseudobinary alloy NWs using the vapor transport method. Compositional tuning results in the phase evolution from the zinc blende (ZB) (x < 0.4) to the wurtzite (WZ) phase (x > 0.7). A coexistence of ZB and WZ phases (x = 0.4-0.7) is also observed. In the intermediate phase coexistence range, a core-shell structure is produced with a composition of x = 0.4 and 0.7 for the core and shell, respectively. The band gap (2.4-3.7 eV) increases nonlinearly with increasing x, showing a significant bowing phenomenon. The phase evolution leads to enhanced photoluminescence emission. Strikingly, the photoluminescence spectrum shows a blue-shift (70 meV for x = 0.9) with increasing excitation power, and a wavelength-dependent decay time. Based on the photoluminescence data, we propose a type-II pseudobinary heterojunction band structure for the single-crystalline WZ phase ZnS-rich NWs. The slight incorporation of GaP into the ZnS induces a higher photocurrent and excellent photocurrent stability, which opens up a new strategy for enhancing the performance of photodetectors.
authors.affiliation: Department of Chemistry, Korea University , Jochiwon 339-700, Korea.
authors.forename: Kidong
authors.initials: K
authors.lastname: Park
authors.forename: Jung Ah
authors.initials: JA
authors.lastname: Lee
authors.forename: Hyung Soon
authors.initials: HS
authors.lastname: Im
authors.forename: Chan Su
authors.initials: CS
authors.lastname: Jung
authors.forename: Han Sung
authors.initials: HS
authors.lastname: Kim
authors.forename: Jeunghee
authors.initials: J
authors.lastname: Park
authors.forename: Chang-Lyoul
authors.initials: CL
authors.lastname: Lee
keywords: GaPZnS nanowires; band gap; pseudobinary; quaternary composition tuning; wurtzite,-zinc blende phase evolution