China graphite molds for steel casting Manufacturers, Suppliers, Factory

The development of high-powered blue and UV LEDs has enabled the creation of full-color LED TV displays, as well as white LED automotive and domestic lighting. These LEDs are based on Gallium Nitride, which is deposited on substrate wafers supported by CVD SiC-coated graphite susceptor using the MOCVD process.

Gallium oxide (Ga2O3) as an "ultra-wide bandgap semiconductor" material has garnered sustained attention. Ultra-wide bandgap semiconductors fall under the category of "fourth-generation semiconductors," and in comparison to third-generation semiconductors such as silicon carbide (SiC) and gallium nitride (GaN), gallium oxide boasts a bandgap width of 4.9eV, surpassing silicon carbide's 3.2eV and gallium nitride's 3.39eV. A wider bandgap implies that electrons require more energy to transition from the valence band to the conduction band, endowing gallium oxide with characteristics like high voltage resistance, high-temperature tolerance, high power capability, and radiation resistance.

Epitaxial growth refers to the process of growing a crystallographically well-ordered monocrystalline layer on a substrate. Generally speaking, epitaxial growth involves the cultivation of a crystal layer on a single-crystal substrate, with the grown layer sharing the same crystallographic orientation as the original substrate. Epitaxy is extensively utilized in semiconductor manufacturing, such as the production of epitaxial silicon wafers in the integrated circuit industry.

Within the silicon carbide (SiC) industry chain, substrate suppliers hold significant leverage, primarily due to value distribution. SiC substrates account for 47% of the total value, followed by epitaxial layers at 23%, while device design and manufacturing constitute the remaining 30%. This inverted value chain stems from the high technological barriers inherent to substrate and epitaxial layer production. Three major challenges plague SiC substrate growth: stringent growth conditions, slow growth rates, and demanding crystallographic requirements. These complexities contribute to increased processing difficulty, ultimately resulting in low product yields and high costs. Furthermore, the epitaxial layer’s thickness and doping concentration are critical parameters directly impacting the final device performance.

Gallium Nitride (GaN) epitaxial wafer growth is a complex process, often utilizing a two-step method. This method involves several critical stages, including high-temperature baking, buffer layer growth, recrystallization, and annealing. By meticulously controlling the temperature throughout these stages, the two-step growth method effectively prevents wafer warping caused by lattice mismatch or stress, making it the predominant fabrication method for GaN epitaxial wafers globally.

The development of 3C-SiC, a significant polytype of silicon carbide, reflects the continuous advancement of semiconductor material science. In the 1980s, Nishino et al. first achieved a 4 μm thick 3C-SiC film on a silicon substrate using chemical vapor deposition (CVD)[1], laying the foundation for 3C-SiC thin-film technology.