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Observation and tunability of room temperature photoluminescence of GaAs/GaInAs core-multiple-quantum-well shell nanowire structure grown on Si (100) by molecular beam epitaxy.

Park KW, Park CY, Ravindran S, Jang JS, Jo YR, Kim BJ, Lee YT - Nanoscale Res Lett (2014)

Bottom Line: The GaAs/GaInAs core-MQW shell NW surrounded by AlGaAs also shows an enhanced PL intensity due to the improved carrier confinement owing to the presence of an AlGaAs clad layer.The inclined growth of the GaAs NWs produces a core-MQW shell structure having a different PL peak position than that of planar QWs.The PL emission by MQW shell and the ability to tune the PL peak position by varying the shell width make such core-shell NWs highly attractive for realizing next generation ultrasmall light sources and other optoelectronics devices. 81.07.Gf; 81.15.Hi; 78.55.Cr.

View Article: PubMed Central - HTML - PubMed

Affiliation: School of Information and Communications, Gwangju Institute of Science and Technology, 123 Cheomdangwagi-ro, Buk-gu, Gwangju 500-712, Republic of Korea.

ABSTRACT

Unlabelled: We report the observation of room temperature photoluminescence (PL) emission from GaAs/GaInAs core-multiple-quantum-well (MQW) shell nanowires (NWs) surrounded by AlGaAs grown by molecular beam epitaxy (MBE) using a self-catalyzed technique. PL spectra of the sample show two PL peaks, originating from the GaAs core NWs and the GaInAs MQW shells. The PL peak from the shell structure red-shifts with increasing well width, and the peak position can be tuned by adjusting the width of the MQW shell. The GaAs/GaInAs core-MQW shell NW surrounded by AlGaAs also shows an enhanced PL intensity due to the improved carrier confinement owing to the presence of an AlGaAs clad layer. The inclined growth of the GaAs NWs produces a core-MQW shell structure having a different PL peak position than that of planar QWs. The PL emission by MQW shell and the ability to tune the PL peak position by varying the shell width make such core-shell NWs highly attractive for realizing next generation ultrasmall light sources and other optoelectronics devices.

Pacs: 81.07.Gf; 81.15.Hi; 78.55.Cr.

No MeSH data available.


SEM images of GaAs NWs on (100) silicon substrate with different growth temperatures. (a) 600°C, (b) 630°C, (c) 650°C, (d) 670°C, (e) close-up view of a GaAs NW core, and (f) EDX spectra taken at the middle [B] and top [A] of a GaAs NW core (see Figure 1e). The inset of Figure 1e shows the clear formation of a hexagonally shaped NW.
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Figure 1: SEM images of GaAs NWs on (100) silicon substrate with different growth temperatures. (a) 600°C, (b) 630°C, (c) 650°C, (d) 670°C, (e) close-up view of a GaAs NW core, and (f) EDX spectra taken at the middle [B] and top [A] of a GaAs NW core (see Figure 1e). The inset of Figure 1e shows the clear formation of a hexagonally shaped NW.

Mentions: Figure 1a,b,c,d,e shows the SEM images of the GaAs NWs grown at different temperatures. As shown in Figure 1, most of the GaAs NWs grown on (100) silicon substrate are oriented at an angle of 35° with respect to the substrate surface, indicating that the wires follow the lattice orientation of the substrate. As the growth temperature increases from 600°C to 670°C, the density of the NW as well as the length of individual NWs increases, as can be seen from Figure 1a,b,c,d. Furthermore, with the increase in growth temperature from 600°C to 630°C, it was found that the diameter of the NWs increases from 140 to 590 nm and then decreases to 170 nm at a growth temperature of 670°C, and a similar behavior has been reported in ref. [31]. On the other hand, with increasing growth temperature, the NW length increases from 1.3 to 13.3 μm. Considering the requirements that the NW core should be rigid and long enough so as to be used for depositing the shell material, 650°C was chosen as the optimum growth temperature for forming the GaAs core. To investigate the constituent elements of the grown NW, EDX studies were carried out. The EDX spectra shown in Figure 1f, taken from the top and middle point of the grown NW, reveal that it consists of Ga and As elements, and the relatively similar amplitude of Ga and As peaks from the two different points indicate that the composition of the grown NW is similar along its axis. The cross-section of the grown nanowire was hexagonal [32] as shown in the inset of Figure 1e having a mixture of wurtzite (WZ) and zinc blende (ZB) structures. This is due to the comparable free energies of WZ and ZB structures as the diameter of the grown nanowire exceeds beyond the critical diameter (approximately 10 to 30 nm) [33]. It is noteworthy that the cross-section of the stacking-fault-free ZB GaAs nanowire was square in shape [33].


Observation and tunability of room temperature photoluminescence of GaAs/GaInAs core-multiple-quantum-well shell nanowire structure grown on Si (100) by molecular beam epitaxy.

Park KW, Park CY, Ravindran S, Jang JS, Jo YR, Kim BJ, Lee YT - Nanoscale Res Lett (2014)

SEM images of GaAs NWs on (100) silicon substrate with different growth temperatures. (a) 600°C, (b) 630°C, (c) 650°C, (d) 670°C, (e) close-up view of a GaAs NW core, and (f) EDX spectra taken at the middle [B] and top [A] of a GaAs NW core (see Figure 1e). The inset of Figure 1e shows the clear formation of a hexagonally shaped NW.
© Copyright Policy - open-access
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4257527&req=5

Figure 1: SEM images of GaAs NWs on (100) silicon substrate with different growth temperatures. (a) 600°C, (b) 630°C, (c) 650°C, (d) 670°C, (e) close-up view of a GaAs NW core, and (f) EDX spectra taken at the middle [B] and top [A] of a GaAs NW core (see Figure 1e). The inset of Figure 1e shows the clear formation of a hexagonally shaped NW.
Mentions: Figure 1a,b,c,d,e shows the SEM images of the GaAs NWs grown at different temperatures. As shown in Figure 1, most of the GaAs NWs grown on (100) silicon substrate are oriented at an angle of 35° with respect to the substrate surface, indicating that the wires follow the lattice orientation of the substrate. As the growth temperature increases from 600°C to 670°C, the density of the NW as well as the length of individual NWs increases, as can be seen from Figure 1a,b,c,d. Furthermore, with the increase in growth temperature from 600°C to 630°C, it was found that the diameter of the NWs increases from 140 to 590 nm and then decreases to 170 nm at a growth temperature of 670°C, and a similar behavior has been reported in ref. [31]. On the other hand, with increasing growth temperature, the NW length increases from 1.3 to 13.3 μm. Considering the requirements that the NW core should be rigid and long enough so as to be used for depositing the shell material, 650°C was chosen as the optimum growth temperature for forming the GaAs core. To investigate the constituent elements of the grown NW, EDX studies were carried out. The EDX spectra shown in Figure 1f, taken from the top and middle point of the grown NW, reveal that it consists of Ga and As elements, and the relatively similar amplitude of Ga and As peaks from the two different points indicate that the composition of the grown NW is similar along its axis. The cross-section of the grown nanowire was hexagonal [32] as shown in the inset of Figure 1e having a mixture of wurtzite (WZ) and zinc blende (ZB) structures. This is due to the comparable free energies of WZ and ZB structures as the diameter of the grown nanowire exceeds beyond the critical diameter (approximately 10 to 30 nm) [33]. It is noteworthy that the cross-section of the stacking-fault-free ZB GaAs nanowire was square in shape [33].

Bottom Line: The GaAs/GaInAs core-MQW shell NW surrounded by AlGaAs also shows an enhanced PL intensity due to the improved carrier confinement owing to the presence of an AlGaAs clad layer.The inclined growth of the GaAs NWs produces a core-MQW shell structure having a different PL peak position than that of planar QWs.The PL emission by MQW shell and the ability to tune the PL peak position by varying the shell width make such core-shell NWs highly attractive for realizing next generation ultrasmall light sources and other optoelectronics devices. 81.07.Gf; 81.15.Hi; 78.55.Cr.

View Article: PubMed Central - HTML - PubMed

Affiliation: School of Information and Communications, Gwangju Institute of Science and Technology, 123 Cheomdangwagi-ro, Buk-gu, Gwangju 500-712, Republic of Korea.

ABSTRACT

Unlabelled: We report the observation of room temperature photoluminescence (PL) emission from GaAs/GaInAs core-multiple-quantum-well (MQW) shell nanowires (NWs) surrounded by AlGaAs grown by molecular beam epitaxy (MBE) using a self-catalyzed technique. PL spectra of the sample show two PL peaks, originating from the GaAs core NWs and the GaInAs MQW shells. The PL peak from the shell structure red-shifts with increasing well width, and the peak position can be tuned by adjusting the width of the MQW shell. The GaAs/GaInAs core-MQW shell NW surrounded by AlGaAs also shows an enhanced PL intensity due to the improved carrier confinement owing to the presence of an AlGaAs clad layer. The inclined growth of the GaAs NWs produces a core-MQW shell structure having a different PL peak position than that of planar QWs. The PL emission by MQW shell and the ability to tune the PL peak position by varying the shell width make such core-shell NWs highly attractive for realizing next generation ultrasmall light sources and other optoelectronics devices.

Pacs: 81.07.Gf; 81.15.Hi; 78.55.Cr.

No MeSH data available.