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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.


Cross-sectional HAADF-STEM image, close-view of the cross-section BF TEM, and line scan EDX profile. (a) Cross-sectional HAADF STEM image of the grown GaAs/GaInAs core-MQWs (expected GaInAs shell thickness of 16 nm) surrounded by AlGaAs clads grown on GaAs core and (b) close view of the cross-section BF TEM of the boxed area clearly shows multiple layers including GaAs/GaInAs MQWs and AlGaAs clads. (c) Line scan EDX profile (taken along the white dotted line shown inside the dotted box in Figure 5a) shows GaAs, GaInAs, and AlGaAs shells. The actual GaInAs shell thickness of the 16-nm-thick GaInAs shell was approximately 12 nm. The yellow regions have a higher In composition and represent the GaInAs well layers.
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Figure 5: Cross-sectional HAADF-STEM image, close-view of the cross-section BF TEM, and line scan EDX profile. (a) Cross-sectional HAADF STEM image of the grown GaAs/GaInAs core-MQWs (expected GaInAs shell thickness of 16 nm) surrounded by AlGaAs clads grown on GaAs core and (b) close view of the cross-section BF TEM of the boxed area clearly shows multiple layers including GaAs/GaInAs MQWs and AlGaAs clads. (c) Line scan EDX profile (taken along the white dotted line shown inside the dotted box in Figure 5a) shows GaAs, GaInAs, and AlGaAs shells. The actual GaInAs shell thickness of the 16-nm-thick GaInAs shell was approximately 12 nm. The yellow regions have a higher In composition and represent the GaInAs well layers.

Mentions: Figure 5a shows such an HAADF STEM image of a NW with the complete structure having a 16-nm-thick GaInAs shell, and the BF TEM close-up view of the white boxed region in Figure 5a is shown in Figure 5b. It can be seen that the cross-sectional image clearly reveals the two GaInAs quantum wells, where each GaInAs well is sandwiched between GaAs barriers. The innermost AlGaAs layer that surrounds the GaAs nanowire and the outermost AlGaAs layer that surrounds the shell structure can also be seen. The cross-sectional TEM measurement thus confirms the formation of GaInAs quantum-well layers, GaAs barriers, and AlGaAs clad layers. The cross-sectional image of Figure 5a also reveals that the thickness of the shell that surrounds the nanowire is not uniform. The shell that is on the facet of the nanowire which directly faces the molecular beam flux is thicker while the shell that is not directly exposed is thinner [9]. From the inset of Figure 5b, it is found that the nanowire is grown along [111] direction. The line scan EDX profile of the NW cross-section taken along the outermost AlGaAs shell to the GaAs core (the white dotted line shown inside the dotted box in Figure 5a) depicted in Figure 5c clearly reveals the presence of GaAs, GaInAs, and AlGaAs shells. The EDX line scan does not provide quantitative information of the compositing layers due to the limited spatial resolution of EDX and/or sample drift during measurement. However, via spot EDX measurement, the quantitative details of the compositing layers can be obtained, and the regions having higher In composition represent the GaInAs QW layers.


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)

Cross-sectional HAADF-STEM image, close-view of the cross-section BF TEM, and line scan EDX profile. (a) Cross-sectional HAADF STEM image of the grown GaAs/GaInAs core-MQWs (expected GaInAs shell thickness of 16 nm) surrounded by AlGaAs clads grown on GaAs core and (b) close view of the cross-section BF TEM of the boxed area clearly shows multiple layers including GaAs/GaInAs MQWs and AlGaAs clads. (c) Line scan EDX profile (taken along the white dotted line shown inside the dotted box in Figure 5a) shows GaAs, GaInAs, and AlGaAs shells. The actual GaInAs shell thickness of the 16-nm-thick GaInAs shell was approximately 12 nm. The yellow regions have a higher In composition and represent the GaInAs well layers.
© Copyright Policy - open-access
Related In: Results  -  Collection

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Figure 5: Cross-sectional HAADF-STEM image, close-view of the cross-section BF TEM, and line scan EDX profile. (a) Cross-sectional HAADF STEM image of the grown GaAs/GaInAs core-MQWs (expected GaInAs shell thickness of 16 nm) surrounded by AlGaAs clads grown on GaAs core and (b) close view of the cross-section BF TEM of the boxed area clearly shows multiple layers including GaAs/GaInAs MQWs and AlGaAs clads. (c) Line scan EDX profile (taken along the white dotted line shown inside the dotted box in Figure 5a) shows GaAs, GaInAs, and AlGaAs shells. The actual GaInAs shell thickness of the 16-nm-thick GaInAs shell was approximately 12 nm. The yellow regions have a higher In composition and represent the GaInAs well layers.
Mentions: Figure 5a shows such an HAADF STEM image of a NW with the complete structure having a 16-nm-thick GaInAs shell, and the BF TEM close-up view of the white boxed region in Figure 5a is shown in Figure 5b. It can be seen that the cross-sectional image clearly reveals the two GaInAs quantum wells, where each GaInAs well is sandwiched between GaAs barriers. The innermost AlGaAs layer that surrounds the GaAs nanowire and the outermost AlGaAs layer that surrounds the shell structure can also be seen. The cross-sectional TEM measurement thus confirms the formation of GaInAs quantum-well layers, GaAs barriers, and AlGaAs clad layers. The cross-sectional image of Figure 5a also reveals that the thickness of the shell that surrounds the nanowire is not uniform. The shell that is on the facet of the nanowire which directly faces the molecular beam flux is thicker while the shell that is not directly exposed is thinner [9]. From the inset of Figure 5b, it is found that the nanowire is grown along [111] direction. The line scan EDX profile of the NW cross-section taken along the outermost AlGaAs shell to the GaAs core (the white dotted line shown inside the dotted box in Figure 5a) depicted in Figure 5c clearly reveals the presence of GaAs, GaInAs, and AlGaAs shells. The EDX line scan does not provide quantitative information of the compositing layers due to the limited spatial resolution of EDX and/or sample drift during measurement. However, via spot EDX measurement, the quantitative details of the compositing layers can be obtained, and the regions having higher In composition represent the GaInAs QW layers.

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.