Ternary III-V nanowires （NWs） cover a wide range of wavelengths in the solar spectrum and would greatly benefit from being synthesized as position-controlled arrays for improved vertical yield, reproducibility, and ...Ternary III-V nanowires （NWs） cover a wide range of wavelengths in the solar spectrum and would greatly benefit from being synthesized as position-controlled arrays for improved vertical yield, reproducibility, and tunable optical absorption. Here, we report on successful selective-area epitaxy of metal-particle-free vertical InxGa1-xP NW arrays using metal-organic vapor phase epitaxy and detail their optical properties. A systematic growth study establishes the range of suitable growth parameters to obtain uniform NW growth over a large array. The optical properties of the NWs were characterized by room-temperature cathodoluminescence spectroscopy. Tunability of the emission wavelength from 870 nm to approximately 800 nm was achieved. Transmission electron microscopy and energy dispersive X-ray measurements performed on cross- section samples revealed a pure wurtzite crystal structure with very few stacking faults and a slight composition gradient along the NW growth axis.展开更多
Catalyst-free InGaAs nanowires grown by selective area epitaxy are promising building blocks for future optoelectronic devices in the infrared spectral region.Despite progress,the role of pattern geometry and growth p...Catalyst-free InGaAs nanowires grown by selective area epitaxy are promising building blocks for future optoelectronic devices in the infrared spectral region.Despite progress,the role of pattern geometry and growth parameters on the composition,microstructure,and optical properties of InGaAs nanowires is still unresolved.Here,we present an optimised growth parameter window to achieve highly uniform In1-xGaxAs nanowire arrays on GaAs(111)B substrate over an extensive range of Ga concentrations,from 0.1 to 0.91,by selective-area metal-organic vapor-phase epitaxy.We observe that the Ga content always increases with decreasing In/(Ga+In)precursor ratio and group V flow rate and increasing growth temperature.The increase in Ga content is supported by a blue shift in the photoluminescence peak emission.The geometry of the nanowire arrays also plays an important role in the resulting composition.Notably,increasing the nanowire pitch size from 0.6 to 2μm in a patterned array shifts the photoluminescence peak emission by up to 120 meV.Irrespective of these growth and geometry parameters,the Ga content determines the crystal structure,resulting in a predominantly wurtzite structure for xGa≤0.3 and a predominantly zinc blende phase for xGa≥0.65.These insights on the factors controlling the composition of InGaAs nanowires grown by a scalable catalyst-free approach provide directions for engineering nanowires as functional components of future optoelectronic devices.展开更多
文摘Ternary III-V nanowires （NWs） cover a wide range of wavelengths in the solar spectrum and would greatly benefit from being synthesized as position-controlled arrays for improved vertical yield, reproducibility, and tunable optical absorption. Here, we report on successful selective-area epitaxy of metal-particle-free vertical InxGa1-xP NW arrays using metal-organic vapor phase epitaxy and detail their optical properties. A systematic growth study establishes the range of suitable growth parameters to obtain uniform NW growth over a large array. The optical properties of the NWs were characterized by room-temperature cathodoluminescence spectroscopy. Tunability of the emission wavelength from 870 nm to approximately 800 nm was achieved. Transmission electron microscopy and energy dispersive X-ray measurements performed on cross- section samples revealed a pure wurtzite crystal structure with very few stacking faults and a slight composition gradient along the NW growth axis.
文摘Catalyst-free InGaAs nanowires grown by selective area epitaxy are promising building blocks for future optoelectronic devices in the infrared spectral region.Despite progress,the role of pattern geometry and growth parameters on the composition,microstructure,and optical properties of InGaAs nanowires is still unresolved.Here,we present an optimised growth parameter window to achieve highly uniform In1-xGaxAs nanowire arrays on GaAs(111)B substrate over an extensive range of Ga concentrations,from 0.1 to 0.91,by selective-area metal-organic vapor-phase epitaxy.We observe that the Ga content always increases with decreasing In/(Ga+In)precursor ratio and group V flow rate and increasing growth temperature.The increase in Ga content is supported by a blue shift in the photoluminescence peak emission.The geometry of the nanowire arrays also plays an important role in the resulting composition.Notably,increasing the nanowire pitch size from 0.6 to 2μm in a patterned array shifts the photoluminescence peak emission by up to 120 meV.Irrespective of these growth and geometry parameters,the Ga content determines the crystal structure,resulting in a predominantly wurtzite structure for xGa≤0.3 and a predominantly zinc blende phase for xGa≥0.65.These insights on the factors controlling the composition of InGaAs nanowires grown by a scalable catalyst-free approach provide directions for engineering nanowires as functional components of future optoelectronic devices.
