State-of-the-art and prospective progress of growing AlN substrates by physical vapor transport

Yao, Xiaogang; Zhang, Baoguo; Hu, Haixiao; Wang, Yong; Kong, Zhen; Wu, Yongzhong; Shao, Yongliang

doi:10.1016/j.jcrysgro.2023.127276

Cited by 11 publications

(2 citation statements)

References 106 publications

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“…As the typical representative of the wide band gap semiconductor, aluminum nitride (AlN) crystals have the advantages of wide band gap (6.2 eV), high saturated carrier drift velocity, high thermal stability, high breakdown field strength, and high surface acoustic velocity. It has good application prospects in the preparation of high-temperature, high-frequency, high-power electronic devices, especially in blue-UV solid-state laser diodes, − lasers, and GaN-based high-electron-mobility transistors (HEMT) devices and substrates for solar blind AlGaN ultraviolet detector devices. − At present, the PVT (physical vapor transport) method is widely recognized as the effective way to prepare large-sized AlN single crystals due to its advantages such as the fast growth rate and high crystalline quality. − …”

Section: Introductionmentioning

confidence: 99%

Effect of Air Layer Thickness on AlN Crystal Growth by the PVT Method

Cao,

Wang,

et al. 2024

Crystal Growth & Design

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The temperature distribution in the crucible plays a decisive role in increasing the growth rate and improving the quality of AlN crystals. Among the many variables affecting the temperature distribution, the air layer is often neglected. In this article, the influence of temperature and flow fields in crucibles with different air layer thicknesses on AlN crystal growth is investigated by numerical simulation and experimental results for the first time. The results show that the air layer thickness is positively related to the temperature gradient in the crucible. The greater the thickness of the air layer, the slower is the growth rate and gradual the decrease of the convexity of the crystal surface. In addition, it was also found that the vertical shear stress gradually increased in the first 7 h and gradually decreased from 7 to 25 h by the stress analysis. The dislocation density is in line with the distribution of the stresses, and the area of the stresses elevated contacts the tungsten metal. Under the condition of the air layer thickness of 10 mm, the crystal interface is slightly convex, the mass transfer route is shorter, the growth rate is moderate, and the shear stress is small, which are suitable for the growth of small-sized AlN crystals. These results demonstrate the feasibility of the simulation results and are supported by the available experimental data, which will provide important directions for the growth of high-quality AlN crystals.

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Section: Introductionmentioning

confidence: 99%

Effect of Air Layer Thickness on AlN Crystal Growth by the PVT Method

Cao,

Wang,

et al. 2024

Crystal Growth & Design

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“…However, the conventional PVT method relies on the sublimation of AlN powder, which demands extremely high temperatures (2000-2300 • C). The strong activity of Al vapor at such temperatures usually poses challenges, leading to the corrosion and deterioration of reactor parts and crucibles [9]. Alternatively, the vaporization of Al metal in a nitrogen (N 2 ) atmosphere could present a promising avenue for growing AlN at lower temperatures [10].…”

Section: Introductionmentioning

confidence: 99%

Growth of Spontaneous Nucleation AlN Crystals by Al-Base Alloy Evaporation in Nitrogen Atmosphere

Tao,

Xu,

Chen

et al. 2024

Crystals

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Aluminum nitride (AlN) crystals with areas ranging from 1 mm2 to 2 mm2 were successfully grown through spontaneous nucleation at 1700 °C using a modified vapor transport method. In this approach, Cu–Al alloy served as the source of aluminum (Al), and nitrogen (N2) was employed as the nitrogen source. The morphology and crystalline quality of the AlN crystals were characterized by a stereo microscope, Raman spectrometer, photoluminescence (PL) and secondary-ion mass spectrometry (SIMS). Deposited on the graphite lid, the as-grown AlN crystals exhibited both rectangular and hexagonal shapes, identified as m-plane and c-plane AlN, respectively, based on Raman spectroscopy. The full width half maximum (FWHM) values of E2 (high) for the rectangular and hexagonal grains were measured to be 6.00 cm−1 and 6.06 cm−1, respectively, indicating high crystalline quality. However, PL and SIMS analysis indicated the presence of impurities associated with oxygen in the crystals. This paper elucidates the growth mechanism of the modified vapor transport method and highlights the role of the Cu–Al alloy in sustaining reactions at lower temperatures. The addition of copper (Cu) not only facilitates sustainable reactions, but also provides a novel perspective for the growth of AlN single crystals.

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Enhanced Laser Damage Threshold in Optically Addressable Light Valves via Aluminum Nitride Photoconductors

Ghandiparsi,

Chatterjee,

Shen

et al. 2024

Adv Materials Inter

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Optically addressable light valves (OALVs) are specialized optical components utilized for spatial beam shaping in various laser‐based applications, including optics damage mitigation, and enhanced functionality in diode‐based additive manufacturing requiring high intensities. Current state‐of‐the‐art OALVs employ photoconductors such as Bismuth Silicon Oxide (BSO) or Bismuth Germanium Oxide (BGO), which suffer from limited laser‐induced damage thresholds (LiDT) and inadequate thermal conductivities, thus restricting their use in high peak and average power applications. Aluminum nitride (AlN), an emerging ultra‐wide band gap (UWBG) III–V semiconductor, offers promising optoelectronic properties and superior thermal conductivity (>300 Wm−1K−1 at 298° K, compared to BSO's 3.29 Wm−1K−1). In this study, the first AlN‐based OALVs are designed, fabricated, and experimentally demonstrated using commercially available single‐crystal AlN substrates. These AlN‐based OALVs have shown clear superiority over BSO and BGO‐based devices. Design considerations for OALVs incorporating UWBG photoconductors are discussed, and the photoresponsivity from defect‐mediated sub‐bandgap absorption in AlN crystals is verified as sufficient for OALVs operating under high light fluences. The optimum driving voltage for the AlN‐based OALV is determined to be ≈ 45 Vpp at 100 Hz, achieving a transmittance of 91.3%, an extinction ratio (ER) of more than 100, and a 51:1 image contrast.

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State-of-the-art and prospective progress of growing AlN substrates by physical vapor transport

Cited by 11 publications

References 106 publications

Effect of Air Layer Thickness on AlN Crystal Growth by the PVT Method

Effect of Air Layer Thickness on AlN Crystal Growth by the PVT Method

Growth of Spontaneous Nucleation AlN Crystals by Al-Base Alloy Evaporation in Nitrogen Atmosphere

Enhanced Laser Damage Threshold in Optically Addressable Light Valves via Aluminum Nitride Photoconductors

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