Ultrawide-bandgap semiconductor AlN crystals: growth and applications

Abstract

This review systematically summarizes the latest research advances of AlN crystals grown by the PVT method and their applications.

Recent Advances in Fabricating Wurtzite AlN Film on (0001)-Plane Sapphire Substrate

“…As a representative ultrawide bandgap (UWBG) semiconductor material, wurtzite aluminum nitride (AlN) material has many excellent properties such as high electron mobility (1100 cm 2 /Vs), high breakdown voltage (11.7 MV/cm), high piezoelectric coefficient, high thermal conductivity (320 W/m•K), high hardness (nine on the Mohs scale), high corrosion resistance, high chemical and thermal stability, as well as high bulk acoustic wave velocity (11,270 m/s) [1][2][3]. Therefore, it is quite suitable to fabricate next-generation power electronic devices, energy harvesting devices, and acoustic devices that can operate in the harsh environment [4][5][6].…”

“…Growing bulk crystals from the melt, which is performed for most other III-V semiconductors, is no longer applicable to AlN because ultrahigh temperature and pressure are needed. Nowadays, bulk AlN crystals are nearly exclusively obtained by using the physical vapor transport (PVT) method (sublimation and recondensation), which has achieved low TDDs of 10 2 -10 5 cm −2 [2]. Nevertheless, it still cannot solve the typical problems such as small size (<60 mm), high impurity concentration (10 18 -10 19 cm −3 ), poor ultraviolet transparency (α 265-280 nm = 14-21 cm −1 ), and high cost (>9000 USD/2 inch) [16].…”

Influence of Different Heater Structures on the Temperature Field of AlN Crystal Growth by Resistance Heating

“…In recent years, ultra-wide bandgap semiconductor materials represented by aluminum nitride (AlN) have been widely used in different fields due to their excellent high-frequency power characteristics, stable high-temperature performance, low energy loss, and good UV transmittance [ 1 , 2 , 3 ]. Therefore, it has great application prospects in the fields of high-efficiency optoelectronic devices, high-power high-frequency electronic devices, ultra-high voltage power electronic devices, deep ultraviolet warning and guidance, and deep ultraviolet light-emitting diode (DUV LED) disinfection [ 4 , 5 , 6 , 7 , 8 ].…”

“…The comprehensive performance is 10–15 times that of SiC and GaN power devices. So far, a variety of methods have been developed to prepare AlN crystals, which mainly include hydride vapor phase epitaxy (HVPE) [ 3 ], molecular beam epitaxy (MBE), metal organic compound vapor deposition (MOCVD), solution growth, physical vapor transport (PVT) [ 2 , 10 ], and so on. The PVT method has the advantages of a simple growth process, fast growth rate, low dislocation density, good crystal integrity, and high safety, and has been proven to be one of the most effective methods for the preparation of AlN bulk single crystals [ 10 , 11 , 12 , 13 , 14 ].…”

“…The PVT method has the advantages of a simple growth process, fast growth rate, low dislocation density, good crystal integrity, and high safety, and has been proven to be one of the most effective methods for the preparation of AlN bulk single crystals [ 10 , 11 , 12 , 13 , 14 ]. In recent years, AlN crystal growth has mainly focused on the following three strategies [ 2 , 10 ]: (1) spontaneous nucleation, (2) homoepitaxial growth on AlN substrates, and (3) heteroepitaxial growth on SiC substrates. For spontaneous nucleation growth, the AlN extension angle is small (10–15°), and it is difficult and time-consuming to extend the diameter.…”