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Environmentally friendly method to grow wide-bandgap semiconductor aluminum nitride crystals: Elementary source vapor phase epitaxy.

Wu P, Funato M, Kawakami Y - Sci Rep (2015)

Bottom Line: Herein we propose a novel vapor-phase-epitaxy-based growth method for AlN that does not use toxic materials; the source precursors are elementary aluminum and nitrogen gas.This growth rate is comparable to that by HVPE, and the growth temperature is much lower than that in sublimation.Thus, this study opens up a novel route to achieve environmentally friendly growth of AlN.

View Article: PubMed Central - PubMed

Affiliation: Department of Electronic Science and Engineering, Kyoto University, Kyoto 615-8510, Japan.

ABSTRACT
Aluminum nitride (AlN) has attracted increasing interest as an optoelectronic material in the deep ultraviolet spectral range due to its wide bandgap of 6.0 eV (207 nm wavelength) at room temperature. Because AlN bulk single crystals are ideal device substrates for such applications, the crystal growth of bulky AlN has been extensively studied. Two growth methods seem especially promising: hydride vapor phase epitaxy (HVPE) and sublimation. However, the former requires hazardous gases such as hydrochloric acid and ammonia, while the latter needs extremely high growth temperatures around 2000 °C. Herein we propose a novel vapor-phase-epitaxy-based growth method for AlN that does not use toxic materials; the source precursors are elementary aluminum and nitrogen gas. To prepare our AlN, we constructed a new growth apparatus, which realizes growth of AlN single crystals at a rate of ~18 μm/h at 1550 °C using argon as the source transfer via the simple reaction Al + 1/2N2 → AlN. This growth rate is comparable to that by HVPE, and the growth temperature is much lower than that in sublimation. Thus, this study opens up a novel route to achieve environmentally friendly growth of AlN.

No MeSH data available.


Related in: MedlinePlus

Optical properties of 18-μm-thick AlN assessed by PL at 11.6 K and RT.Because the emission is located at ~390 nm, it is not band edge emission, but a deep level emission that is likely related to Al vacancies and deep donors. Intensity ratio between RT and 11.6 K suggests a high internal quantum efficiency of ~32%.
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f5: Optical properties of 18-μm-thick AlN assessed by PL at 11.6 K and RT.Because the emission is located at ~390 nm, it is not band edge emission, but a deep level emission that is likely related to Al vacancies and deep donors. Intensity ratio between RT and 11.6 K suggests a high internal quantum efficiency of ~32%.

Mentions: The optical properties were assessed by photoluminescence (PL). (See Methods.) Figure 5 shows the PL spectra of the 18-μm-thick AlN layer acquired at RT and 11.6 K. The band edge emission near 6 eV is absent, but a deep level emission is observed at ~390 nm (~3.2 eV). The ratio of the PL integrated intensity at RT against that at 11.6 K is as high as 32%, which is an approximation of the internal quantum efficiency at RT if nonradiative recombination processes at low temperatures are negligible.


Environmentally friendly method to grow wide-bandgap semiconductor aluminum nitride crystals: Elementary source vapor phase epitaxy.

Wu P, Funato M, Kawakami Y - Sci Rep (2015)

Optical properties of 18-μm-thick AlN assessed by PL at 11.6 K and RT.Because the emission is located at ~390 nm, it is not band edge emission, but a deep level emission that is likely related to Al vacancies and deep donors. Intensity ratio between RT and 11.6 K suggests a high internal quantum efficiency of ~32%.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4663762&req=5

f5: Optical properties of 18-μm-thick AlN assessed by PL at 11.6 K and RT.Because the emission is located at ~390 nm, it is not band edge emission, but a deep level emission that is likely related to Al vacancies and deep donors. Intensity ratio between RT and 11.6 K suggests a high internal quantum efficiency of ~32%.
Mentions: The optical properties were assessed by photoluminescence (PL). (See Methods.) Figure 5 shows the PL spectra of the 18-μm-thick AlN layer acquired at RT and 11.6 K. The band edge emission near 6 eV is absent, but a deep level emission is observed at ~390 nm (~3.2 eV). The ratio of the PL integrated intensity at RT against that at 11.6 K is as high as 32%, which is an approximation of the internal quantum efficiency at RT if nonradiative recombination processes at low temperatures are negligible.

Bottom Line: Herein we propose a novel vapor-phase-epitaxy-based growth method for AlN that does not use toxic materials; the source precursors are elementary aluminum and nitrogen gas.This growth rate is comparable to that by HVPE, and the growth temperature is much lower than that in sublimation.Thus, this study opens up a novel route to achieve environmentally friendly growth of AlN.

View Article: PubMed Central - PubMed

Affiliation: Department of Electronic Science and Engineering, Kyoto University, Kyoto 615-8510, Japan.

ABSTRACT
Aluminum nitride (AlN) has attracted increasing interest as an optoelectronic material in the deep ultraviolet spectral range due to its wide bandgap of 6.0 eV (207 nm wavelength) at room temperature. Because AlN bulk single crystals are ideal device substrates for such applications, the crystal growth of bulky AlN has been extensively studied. Two growth methods seem especially promising: hydride vapor phase epitaxy (HVPE) and sublimation. However, the former requires hazardous gases such as hydrochloric acid and ammonia, while the latter needs extremely high growth temperatures around 2000 °C. Herein we propose a novel vapor-phase-epitaxy-based growth method for AlN that does not use toxic materials; the source precursors are elementary aluminum and nitrogen gas. To prepare our AlN, we constructed a new growth apparatus, which realizes growth of AlN single crystals at a rate of ~18 μm/h at 1550 °C using argon as the source transfer via the simple reaction Al + 1/2N2 → AlN. This growth rate is comparable to that by HVPE, and the growth temperature is much lower than that in sublimation. Thus, this study opens up a novel route to achieve environmentally friendly growth of AlN.

No MeSH data available.


Related in: MedlinePlus