Gallium arsenide single crystal growth process of PAM-XIAMEN products is liquid-sealed straight pull method (LEC), vertical Bridgman method (VB), or vertical gradient solidification (VGF), which are current mainstream industrial growth processes. Here is a brief introduction for the gallium arsenide single crystal growth process.
1. LEC for Gallium Arsenide Single Crystal Growth
The LEC method is the main process for growing non-doped semi-insulating gallium arsenide single crystal (SI GaAs). At present, more than 80% of the semi-insulating gallium arsenide single crystals on the market are grown by the LEC method.
The LEC method uses a graphite heater and a PBN crucible, and uses B2O3 as a liquid sealing agent to grow gallium arsenide crystal in an argon atmosphere of 2MPa. The main advantages of the LEC process are high reliability, easy growth of longer large-diameter single crystals, controllable crystal carbon content, and good semi-insulating properties of the crystal.
The main disadvantages are: the chemical dose is difficult to control, the temperature gradient of the thermal field is large (100~150 K/cm), the dislocation density of the crystal is as high as 104 or more and the distribution is uneven.
2. VB for Growing Single-crystalline Gallium Arsenide
The VB method is a crystal growth process developed in the late 1980s. The synthesized gallium arsenide polycrystal, B2O3 and seed crystals are loaded into a PBN crucible and sealed in an evacuated quartz bottle. The furnace body is placed vertically. Then using resistance wire heating, the quartz bottle is placed vertically in the middle of the furnace body.
The gallium arsenide polycrystal is melted at high temperature and then welded to the seed crystal, and then the quartz bottle and crucible are driven by the support rod to move down through the mechanical transmission mechanism. Under a certain temperature gradient, the GaAs single crystal slowly grows upward from the seed crystal end.
The VB method can grow not only low-resistance gallium arsenide single crystal, but also high-resistance semi-insulating gallium arsenide single crystal. The average EPD of the crystals is below 5 000/cm-2.
3. VGF for Growing GaAs Single Crystal
The principles and application areas of the VGF process and the VB process are basically similar.
The biggest difference is that the VGF method cancels the crystal descending carriage mechanism and the rotating mechanism, and the computer precisely controls the thermal field for slow cooling. The growth interface gradually moves upward from the lower end of the melt to complete the gallium arsenide crystal growth. Due to the elimination of the mechanical transmission mechanism, this process makes the crystal growth interface more stable and is
suitable for growing ultra-low dislocation gallium arsenide single crystals.
The disadvantage of the VB and VGF process is that the GaAs crystal growth cannot be observed and judged during the crystal growth process, and the crystal growth cycle is relatively long.
4. Characterization technology of Gallium Arsenide Materials
As a representative of the second-generation semiconductor materials, gallium arsenide single crystal has important applications in high-energy collision physics experiments, aerospace science and technology, and nuclear radioactive waste detection. Thus, it is of great significance to study its radiation effect and anti-radiation ability.
Low-frequency noise has achieved great success in characterizing the radiation damage of silicon devices, and its technical characteristics also meet the technical requirements for characterizing the radiation damage of gallium arsenide materials.