Aluminum nitride (AlN) is a wide-bandgap semiconductor material with excellent thermal conductivity, high breakdown voltage, and good electrical insulation properties. It has a wide range of applications in electronics, optoelectronics, and power devices. However, the growth of high-quality AlN single crystals remains a challenge due to the lack of suitable substrates and growth techniques.
A recent study reports a new method for growing AlN single crystals by sublimation using hot-pressed BN (HPBN or hBN) crucibles. The researchers found that free nucleation of AlN single crystals can be achieved in hBN crucibles without any external catalysts or seed materials. The native AlN single crystals exhibited high crystal quality, low dislocation density, and high optical transparency.
The study, conducted by a research team at Nagoya University in Japan, was published in the journal Applied Physics Letters. The researchers used HPBN crucibles of different sizes and orientations to study the growth behavior of AlN single crystals. They found that the growth rate of AlN single crystals depends largely on the crucible size and orientation. The largest AlN single crystal grown in this study had a diameter of 10 mm and a height of 2 mm.
AlN single crystals grown by this method have great potential in various applications, such as high-power and high-frequency electronic devices, ultraviolet light-emitting diodes, and deep ultraviolet photodetectors. The high thermal conductivity and low thermal expansion coefficient of AlN make it an ideal material for high-temperature applications, such as power electronics and the aerospace industry.
There are several reasons for choosing HBN as a crucible for AlN crystal growth. First, HPBN is a ceramic material made by hot pressing boron nitride powder under high temperature and pressure. HPBN has excellent thermal stability, chemical inertness, and low impurity content, which can ensure the high purity and quality of native AlN single crystals. In contrast, traditional crucibles made of platinum or other metals will introduce impurities and cause contamination during crystal growth.
Second, HPBN has high thermal conductivity and low thermal expansion coefficient, which can provide efficient heat transfer and reduce thermal stress during crystal growth. This is especially important for AlN crystal growth, because AlN has high thermal conductivity and low thermal expansion coefficient. Using HPBN crucibles can also reduce the risk of thermal cracking and improve crystal quality.
Third, HPBN crucibles are easy to manufacture and can be produced in different sizes and shapes to meet the specific needs of AlN crystal growth. Non-Ferrous is one of the major suppliers of HPBN crucibles, offering a wide range of sizes and grades to meet the needs of customers. The largest HPBN crucible size offered by Edgetec is up to 16x16x8 inches, which is suitable for large-scale AlN crystal growth. In conclusion, free nucleation of AlN single crystals in HPBN crucibles by sublimation is a promising technology for growing high-quality AlN single crystals with various applications. Non-Ferrous Crucible Inc. is one of the major suppliers of HBN crucibles, offering a wide range of sizes and grades to meet the needs of customers. The development of this new growth method can enable the commercial production of high-quality AlN single crystals for various industrial applications.