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Intersubband absorption properties of high Al content AlxGa1-xN/GaN multiple quantum wells grown with different interlayers by metal organic chemical vapor deposition.

Sun HH, Guo FY, Li DY, Wang L, Wang DB, Zhao LC - Nanoscale Res Lett (2012)

Bottom Line: High-resolution X-ray diffraction and transmission electron microscopy analyses indicate that good crystalline quality of the AlGaN/GaN MQW layer could be achieved when the AlGaN interlayer is inserted.The ISB absorption with a peak at 3.7 μm was demonstrated in MQW films with AlGaN interlayer.However, we have not observed the infrared absorption in MQW films with GaN/AlN SL interlayer.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Information Materials Science and Technology, Harbin Institute of Technology, Harbin, 150001, China. hh_sun@live.cn.

ABSTRACT
High Al content AlxGa1-xN/GaN multiple quantum well (MQW) films with different interlayers were grown by metal organic chemical vapor deposition. These MQWs were designed to achieve intersubband (ISB) absorption in the mid-infrared spectral range. We have considered two growth conditions, with AlGaN interlayer and GaN/AlN superlattice (SL) interlayer, both deposited on GaN-on-sapphire templates. Atomic force microscopy images show a relatively rough surface with atomic-step terraces and surface depression, mainly dominated by dislocations. High-resolution X-ray diffraction and transmission electron microscopy analyses indicate that good crystalline quality of the AlGaN/GaN MQW layer could be achieved when the AlGaN interlayer is inserted. The ISB absorption with a peak at 3.7 μm was demonstrated in MQW films with AlGaN interlayer. However, we have not observed the infrared absorption in MQW films with GaN/AlN SL interlayer. It is believed that the high dislocation density and weaker polarization that resulted from the rough interface are determinant factors of vanished ISB absorption for MQW films with the GaN/AlN SL interlayer.

No MeSH data available.


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(0002) ω-2θ scan of samples A and B. IL stands for interlayer.
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Figure 2: (0002) ω-2θ scan of samples A and B. IL stands for interlayer.

Mentions: Figure2 illustrates the (0002) ω-2θ scans of different samples. The clearly visible −2 to +1 order satellite peaks indicate a good periodical structure of MQW layers and sharp abruptness of AlGaN/GaN interfaces. For III-nitride films, the full width at half maximum (FWHM) of ω-scan for symmetric (0002) and asymmetric (10–12) reflections was usually adopted to access the threading dislocation density of MQW films and GaN template, respectively. The FWHM of ω-scan for GaN template and MQW films are shown in Table1. Anomalously, the value of FWHM corresponding to MQW films with interlayers is larger than that of the GaN templates. When the interlayer was inserted, the FWHM increased, which seems to contradict the similar result of the traditional scheme[21,22]. Usually, the interlayer blocks the threading dislocation that originated from the GaN template, leading to the decrease of the FWHM of the subsequent film. Furthermore, it is found that the FWHM of the GaN template in sample B is lower than that in sample A; however, the FWHM of the GaN/AlGaN MQW layer in sample B is higher than that in sample A. The tendency is the same under different reflections. To explain the phenomenon, the FWHM broadening factors of ω-scan will be discussed in the following section.


Intersubband absorption properties of high Al content AlxGa1-xN/GaN multiple quantum wells grown with different interlayers by metal organic chemical vapor deposition.

Sun HH, Guo FY, Li DY, Wang L, Wang DB, Zhao LC - Nanoscale Res Lett (2012)

(0002) ω-2θ scan of samples A and B. IL stands for interlayer.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3526456&req=5

Figure 2: (0002) ω-2θ scan of samples A and B. IL stands for interlayer.
Mentions: Figure2 illustrates the (0002) ω-2θ scans of different samples. The clearly visible −2 to +1 order satellite peaks indicate a good periodical structure of MQW layers and sharp abruptness of AlGaN/GaN interfaces. For III-nitride films, the full width at half maximum (FWHM) of ω-scan for symmetric (0002) and asymmetric (10–12) reflections was usually adopted to access the threading dislocation density of MQW films and GaN template, respectively. The FWHM of ω-scan for GaN template and MQW films are shown in Table1. Anomalously, the value of FWHM corresponding to MQW films with interlayers is larger than that of the GaN templates. When the interlayer was inserted, the FWHM increased, which seems to contradict the similar result of the traditional scheme[21,22]. Usually, the interlayer blocks the threading dislocation that originated from the GaN template, leading to the decrease of the FWHM of the subsequent film. Furthermore, it is found that the FWHM of the GaN template in sample B is lower than that in sample A; however, the FWHM of the GaN/AlGaN MQW layer in sample B is higher than that in sample A. The tendency is the same under different reflections. To explain the phenomenon, the FWHM broadening factors of ω-scan will be discussed in the following section.

Bottom Line: High-resolution X-ray diffraction and transmission electron microscopy analyses indicate that good crystalline quality of the AlGaN/GaN MQW layer could be achieved when the AlGaN interlayer is inserted.The ISB absorption with a peak at 3.7 μm was demonstrated in MQW films with AlGaN interlayer.However, we have not observed the infrared absorption in MQW films with GaN/AlN SL interlayer.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Information Materials Science and Technology, Harbin Institute of Technology, Harbin, 150001, China. hh_sun@live.cn.

ABSTRACT
High Al content AlxGa1-xN/GaN multiple quantum well (MQW) films with different interlayers were grown by metal organic chemical vapor deposition. These MQWs were designed to achieve intersubband (ISB) absorption in the mid-infrared spectral range. We have considered two growth conditions, with AlGaN interlayer and GaN/AlN superlattice (SL) interlayer, both deposited on GaN-on-sapphire templates. Atomic force microscopy images show a relatively rough surface with atomic-step terraces and surface depression, mainly dominated by dislocations. High-resolution X-ray diffraction and transmission electron microscopy analyses indicate that good crystalline quality of the AlGaN/GaN MQW layer could be achieved when the AlGaN interlayer is inserted. The ISB absorption with a peak at 3.7 μm was demonstrated in MQW films with AlGaN interlayer. However, we have not observed the infrared absorption in MQW films with GaN/AlN SL interlayer. It is believed that the high dislocation density and weaker polarization that resulted from the rough interface are determinant factors of vanished ISB absorption for MQW films with the GaN/AlN SL interlayer.

No MeSH data available.


Related in: MedlinePlus