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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.


Related in: MedlinePlus

BF TEM, HRTEM, and HAADF STEM images of a nanowire and spot EDX data. (a) BF TEM image of a nanowire with the complete core-MQW shell structure including the outermost AlGaAs layer. (b) HRTEM image of the boxed area in Figure 4a, and the insets show the corresponding FFT patterns from ZB and WZ structures. (c) HAADF STEM image of the same nanowire shown in Figure 4a. The white line shown in the box represents the region along which the spot EDX was measured. (d) Spot EDX data revealing the atomic weight percentage of the constituent elements of the outermost AlGaAs layer in the nanowire shown in Figure 4c. The inset shows the cross-sectional schematic of the nanowire structure shown in Figure 4a. The arrow shown in the inset indicates the layer from which spot EDX is taken.
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Figure 4: BF TEM, HRTEM, and HAADF STEM images of a nanowire and spot EDX data. (a) BF TEM image of a nanowire with the complete core-MQW shell structure including the outermost AlGaAs layer. (b) HRTEM image of the boxed area in Figure 4a, and the insets show the corresponding FFT patterns from ZB and WZ structures. (c) HAADF STEM image of the same nanowire shown in Figure 4a. The white line shown in the box represents the region along which the spot EDX was measured. (d) Spot EDX data revealing the atomic weight percentage of the constituent elements of the outermost AlGaAs layer in the nanowire shown in Figure 4c. The inset shows the cross-sectional schematic of the nanowire structure shown in Figure 4a. The arrow shown in the inset indicates the layer from which spot EDX is taken.

Mentions: Figure 3d shows the spot EDX data taken from ten different points on the GaInAs layer that was situated at a distance of 10 nm away from the nanowire edge. The spacing between each successive point was also 10 nm. Note that the point resolution of the EDX is approximately 1 nm. The average atomic composition of In is 8.0% with a range of deviation of approximately 2.9%, while the average atomic compositions for Ga and As are 39.5% and 53.8% with the range of error of approximately 3.4% and approximately 3.9%, respectively. These values are close to the predicted composition of Ga0.84In0.16As thin film. It is also evident from Figure 3d that the spot EDX from the GaInAs well layer reveals the presence of In, Ga, and As elements, while Al is absent, and hence, no signal corresponding to Al is observed in Figure 3d. The EDX analyses thus confirm the presence of GaInAs in the grown MQW structure, though we are not able to measure the exact thicknesses of the GaInAs and GaAs layers.Figure 4a shows the BF TEM image of a nanowire with the complete core-shell structure including AlGaAs as the outermost layer. To construct this nanowire structure, we added GaAs, GaInAs, GaAs, and AlGaAs layers to the nanowire shown in Figure 3a. The schematic of the core-shell nanowire having all the layers is shown in the inset of Figure 4d. The SAD pattern of the entire nanowire in the inset of Figure 4a is identical to that shown in the inset of Figure 3a, indicating that the outer shells are grown epitaxially on the wire shown in Figure 3a. This is confirmed by the HRTEM image (Figure 4b) and the corresponding FFT images (inset of Figure 4b) of the layer including the AlGaAs outermost layer, demonstrating the presence of both ZB and WZ structures in the layer.


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)

BF TEM, HRTEM, and HAADF STEM images of a nanowire and spot EDX data. (a) BF TEM image of a nanowire with the complete core-MQW shell structure including the outermost AlGaAs layer. (b) HRTEM image of the boxed area in Figure 4a, and the insets show the corresponding FFT patterns from ZB and WZ structures. (c) HAADF STEM image of the same nanowire shown in Figure 4a. The white line shown in the box represents the region along which the spot EDX was measured. (d) Spot EDX data revealing the atomic weight percentage of the constituent elements of the outermost AlGaAs layer in the nanowire shown in Figure 4c. The inset shows the cross-sectional schematic of the nanowire structure shown in Figure 4a. The arrow shown in the inset indicates the layer from which spot EDX is taken.
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Figure 4: BF TEM, HRTEM, and HAADF STEM images of a nanowire and spot EDX data. (a) BF TEM image of a nanowire with the complete core-MQW shell structure including the outermost AlGaAs layer. (b) HRTEM image of the boxed area in Figure 4a, and the insets show the corresponding FFT patterns from ZB and WZ structures. (c) HAADF STEM image of the same nanowire shown in Figure 4a. The white line shown in the box represents the region along which the spot EDX was measured. (d) Spot EDX data revealing the atomic weight percentage of the constituent elements of the outermost AlGaAs layer in the nanowire shown in Figure 4c. The inset shows the cross-sectional schematic of the nanowire structure shown in Figure 4a. The arrow shown in the inset indicates the layer from which spot EDX is taken.
Mentions: Figure 3d shows the spot EDX data taken from ten different points on the GaInAs layer that was situated at a distance of 10 nm away from the nanowire edge. The spacing between each successive point was also 10 nm. Note that the point resolution of the EDX is approximately 1 nm. The average atomic composition of In is 8.0% with a range of deviation of approximately 2.9%, while the average atomic compositions for Ga and As are 39.5% and 53.8% with the range of error of approximately 3.4% and approximately 3.9%, respectively. These values are close to the predicted composition of Ga0.84In0.16As thin film. It is also evident from Figure 3d that the spot EDX from the GaInAs well layer reveals the presence of In, Ga, and As elements, while Al is absent, and hence, no signal corresponding to Al is observed in Figure 3d. The EDX analyses thus confirm the presence of GaInAs in the grown MQW structure, though we are not able to measure the exact thicknesses of the GaInAs and GaAs layers.Figure 4a shows the BF TEM image of a nanowire with the complete core-shell structure including AlGaAs as the outermost layer. To construct this nanowire structure, we added GaAs, GaInAs, GaAs, and AlGaAs layers to the nanowire shown in Figure 3a. The schematic of the core-shell nanowire having all the layers is shown in the inset of Figure 4d. The SAD pattern of the entire nanowire in the inset of Figure 4a is identical to that shown in the inset of Figure 3a, indicating that the outer shells are grown epitaxially on the wire shown in Figure 3a. This is confirmed by the HRTEM image (Figure 4b) and the corresponding FFT images (inset of Figure 4b) of the layer including the AlGaAs outermost layer, demonstrating the presence of both ZB and WZ structures in the layer.

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.


Related in: MedlinePlus