Sapphire Wafer/ Sapphire Substrate

Sapphire belongs to the corundum group of minerals. It is a common coordination oxide crystal. It belongs to the trigonal crystal system. The crystal space group is R3c. The main chemical composition is AI2O3. The material has a mode hardness of up to 9, second only to diamond. Sapphire has good chemical stability, low preparation cost and mature technology, so it has become the main substrate material of GaN-based optoelectronic devices. In addition, it has good dielectric and mechanical properties, and is widely used in flat panel displays, high-efficiency solid-state devices, photoelectric lighting and other fields. Silicon substrates are also widely used as substrate materials. The silicon surface is arranged in a hexagonal shape and the vertical temperature gradient is large, which is conducive to the stable growth of single crystals and is widely used. However, the biggest technical difficulty in fabricating GaN-based LEDs on a silicon substrate is lattice mismatch and thermal mismatch. The lattice mismatch between silicon and gallium nitride is several times that of silicon nitride, which can cause cracking problems.

The semiconductor field usually uses SiC as a sinking material. The thermal conductivity of silicon nitride is higher than that of sapphire. It is easier to dissipate heat than sapphire and has better antistatic ability. However, the cost of silicon nitride is much higher than that of sapphire, and the cost of commercial production high. Although silicon nitride substrates can also be industrialized, they are expensive and have no universal application. Other sinking materials such as GaN, ZnO, etc. are still in the research and development stage, and there is still a long way to go from industrialization.

When selecting a substrate, it is necessary to consider the matching of the substrate material and the epitaxial material. The defect density of the substrate is required to be low, the chemical properties are stable, the temperature is small, it is not easy to corrode, and it cannot chemically react with the epitaxial film, and consider the actual situation. Manufacturing costs in production. The sapphire substrate has good chemical stability, high temperature resistance, high mechanical strength, good heat dissipation under small current conditions, no visible light absorption, moderate price, mature manufacturing technology, and can be commercialized.

Application of Sapphire Substrate in SOS Field