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Fabrication of low-density GaN/AlN quantum dots via GaN thermal decomposition in MOCVD.

Zhang J, Li S, Xiong H, Tian W, Li Y, Fang Y, Wu Z, Dai J, Xu J, Li X, Chen C - Nanoscale Res Lett (2014)

Bottom Line: With an appropriate high anneal temperature under H2 atmosphere, GaN quantum dots (QDs) have been fabricated via GaN thermal decomposition in metal organic chemical vapor deposition (MOCVD).Based on the characterization of atomic force microscopy (AFM), the obtained GaN QDs show good size distribution and have a low density of 2.4 × 10(8) cm(-2).X-ray photoelectron spectroscopy (XPS) analysis demonstrates that the GaN QDs were formed without Ga droplets by thermal decomposition of GaN.

View Article: PubMed Central - HTML - PubMed

Affiliation: Wuhan National Laboratory for Optoelectronics, School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074, People's Republic of China.

ABSTRACT
With an appropriate high anneal temperature under H2 atmosphere, GaN quantum dots (QDs) have been fabricated via GaN thermal decomposition in metal organic chemical vapor deposition (MOCVD). Based on the characterization of atomic force microscopy (AFM), the obtained GaN QDs show good size distribution and have a low density of 2.4 × 10(8) cm(-2). X-ray photoelectron spectroscopy (XPS) analysis demonstrates that the GaN QDs were formed without Ga droplets by thermal decomposition of GaN.

No MeSH data available.


AFM images of samples. Samples (a) A, (b) B, (c) C, (d) D, (e) E, and (f) corresponding the 3D AFM image of sample A.
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Figure 2: AFM images of samples. Samples (a) A, (b) B, (c) C, (d) D, (e) E, and (f) corresponding the 3D AFM image of sample A.

Mentions: The surface morphologies of all samples were studied by atomic force microscopy (AFM), and the results are shown in Figure 2. Compared with the surface morphology of controlled sample D (Figure 2d), it is obvious that GaN decomposition occurs for Sample A (Figure 1a). Figure 1f is the corresponding three-dimensional (3D) AFM image of Figure 1a, in which distributed dots are on terraces and abrupt peaks are to be buried in the side wall, indicating the decomposition process for the formation of GaN dots. As the decomposition occurred toward the inner of the side wall, the abrupt peaks are then exposed to H2 flow and decomposed. Since the heights of peaks decrease faster than the diameters of peaks, the side wall is etched away and the peaks are etched to small dots with a longer etching time, which is consistent with our previous observation [14]. With increasing of the annealing temperature from 1,050°C to 1,100°C, the decomposition of GaN has an interesting phenomenon that the steps disappear and well-shaped dots are just left on a flat surface, as shown in Figure 2b. The obtained GaN QDs show a low density in the magnitude of approximately 108 cm-2. As expected, these dots are etched as the elongation of annealing time from 5 to 8 min, left with atomically flat surface (Figure 2c) similar to that of controlled sample E (Figure 2e). It is clear that surface morphology of the AlN buffer templates before and after annealing in H2 are exactly the same, indicating that no decomposion of AlN takes place at the temperature of 1,100°C. This result is in good agreement with the claim made by Y. Kumagai et al. [21].


Fabrication of low-density GaN/AlN quantum dots via GaN thermal decomposition in MOCVD.

Zhang J, Li S, Xiong H, Tian W, Li Y, Fang Y, Wu Z, Dai J, Xu J, Li X, Chen C - Nanoscale Res Lett (2014)

AFM images of samples. Samples (a) A, (b) B, (c) C, (d) D, (e) E, and (f) corresponding the 3D AFM image of sample A.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4128446&req=5

Figure 2: AFM images of samples. Samples (a) A, (b) B, (c) C, (d) D, (e) E, and (f) corresponding the 3D AFM image of sample A.
Mentions: The surface morphologies of all samples were studied by atomic force microscopy (AFM), and the results are shown in Figure 2. Compared with the surface morphology of controlled sample D (Figure 2d), it is obvious that GaN decomposition occurs for Sample A (Figure 1a). Figure 1f is the corresponding three-dimensional (3D) AFM image of Figure 1a, in which distributed dots are on terraces and abrupt peaks are to be buried in the side wall, indicating the decomposition process for the formation of GaN dots. As the decomposition occurred toward the inner of the side wall, the abrupt peaks are then exposed to H2 flow and decomposed. Since the heights of peaks decrease faster than the diameters of peaks, the side wall is etched away and the peaks are etched to small dots with a longer etching time, which is consistent with our previous observation [14]. With increasing of the annealing temperature from 1,050°C to 1,100°C, the decomposition of GaN has an interesting phenomenon that the steps disappear and well-shaped dots are just left on a flat surface, as shown in Figure 2b. The obtained GaN QDs show a low density in the magnitude of approximately 108 cm-2. As expected, these dots are etched as the elongation of annealing time from 5 to 8 min, left with atomically flat surface (Figure 2c) similar to that of controlled sample E (Figure 2e). It is clear that surface morphology of the AlN buffer templates before and after annealing in H2 are exactly the same, indicating that no decomposion of AlN takes place at the temperature of 1,100°C. This result is in good agreement with the claim made by Y. Kumagai et al. [21].

Bottom Line: With an appropriate high anneal temperature under H2 atmosphere, GaN quantum dots (QDs) have been fabricated via GaN thermal decomposition in metal organic chemical vapor deposition (MOCVD).Based on the characterization of atomic force microscopy (AFM), the obtained GaN QDs show good size distribution and have a low density of 2.4 × 10(8) cm(-2).X-ray photoelectron spectroscopy (XPS) analysis demonstrates that the GaN QDs were formed without Ga droplets by thermal decomposition of GaN.

View Article: PubMed Central - HTML - PubMed

Affiliation: Wuhan National Laboratory for Optoelectronics, School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074, People's Republic of China.

ABSTRACT
With an appropriate high anneal temperature under H2 atmosphere, GaN quantum dots (QDs) have been fabricated via GaN thermal decomposition in metal organic chemical vapor deposition (MOCVD). Based on the characterization of atomic force microscopy (AFM), the obtained GaN QDs show good size distribution and have a low density of 2.4 × 10(8) cm(-2). X-ray photoelectron spectroscopy (XPS) analysis demonstrates that the GaN QDs were formed without Ga droplets by thermal decomposition of GaN.

No MeSH data available.