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

Abstract

Ultrawide bandgap (UWBG) semiconductor materials, with bandgaps far wider than the 3.4 eV of GaN, have attracted great attention recently. As a typical representative, wurtzite aluminum nitride (AlN) material has many advantages including high electron mobility, high breakdown voltage, high piezoelectric coefficient, high thermal conductivity, high hardness, high corrosion resistance, high chemical and thermal stability, high bulk acoustic wave velocity, prominent second-order optical nonlinearity, as well as excellent UV transparency. Therefore, it has wide application prospects in next-generation power electronic devices, energy-harvesting devices, acoustic devices, optical frequency comb, light-emitting diodes, photodetectors, and laser diodes. Due to the lack of low-cost, large-size, and high-ultraviolet-transparency native AlN substrate, however, heteroepitaxial AlN film grown on sapphire substrate is usually adopted to fabricate various devices. To realize high-performance AlN-based devices, we must first know how to obtain high-crystalline-quality and controllable AlN/sapphire templates. This review systematically summarizes the recent advances in fabricating wurtzite AlN film on (0001)-plane sapphire substrate. First, we discuss the control principles of AlN polarity, which greatly affects the surface morphology and crystalline quality of AlN, as well as the electronic and optoelectronic properties of AlN-based devices. Then, we introduce how to control threading dislocations and strain. The physical thoughts of some inspirational growth techniques are discussed in detail, and the threading dislocation density (TDD) values of AlN/sapphire grown by various growth techniques are compiled. We also introduce how to achieve high thermal conductivities in AlN films, which are comparable with those in bulk AlN. Finally, we summarize the future challenge of AlN films acting as templates and semiconductors. Due to the fast development of growth techniques and equipment, as well as the superior material properties, AlN will have wider industrial applications in the future.

A Combination of Ion Implantation and High‐Temperature Annealing: Donor–Acceptor Pairs in Carbon‐Implanted AlN

“…[4,15] AlN crystals can be grown by a wide range of different techniques such as physical vapor transport (PVT), metalorganic vapor phase epitaxy (MOVPE), physical vapor deposition (PVD), and hydride vapor phase epitaxy (HVPE). [2,16] Recently, the recrystallization of submicron thick AlN/sapphire templates using hightemperature annealing (HTA) has gained a lot of interest as a means of manufacturing epitaxial layers with a very high crystallinity. These thin layers are typically deposited using PVD or MOVPE processes and afterward recrystallized at high annealing temperatures of up to 1700 °C, as first introduced by Fukuyama et al, who employed an N 2 -CO atmosphere to prevent decomposition.…”

Vertical and Lateral Etch Survey of Ferroelectric AlN/Al1−xScxN in Aqueous KOH Solutions

“…Based on the crystallinity of AlN/Al 1−x Sc x N, several methods can be used for film growth. Single-crystal AlN can be grown via physical vapor transport (PVT) on substrates up to 60 mm in diameter [ 34 , 35 , 36 ]. Single-crystal Al 1−x Sc x N can be grown by molecular beam epitaxy (MBE) [ 9 ] on 100 mm wafers [ 37 ] with scandium concentration x from 0.06 to 0.36 [ 38 ].…”

Two-dimensional AlN/g-CNs van der Waals type-II heterojunction for water splitting

“…Recently, an AlN monolayer has attracted a lot of attention as a semiconductor material with an ultra-wide band gap. [42][43][44] AlN materials have advantages such as high chemical and thermal stability, 45 high electron mobility, 46 and excellent UV transparency. 47,48 K-doped AlN nanosheets exhibit roomtemperature ferromagnetism at relatively low concentrations, according to calculations by Xiao et al 49 Ouyang et al reported the CO adsorption properties of pristine and defective h-AlN nanosheets.…”