Study On Bridgman Growth Of GaInSb Crystals

As a new type of the ternary compound semiconductor material, with small electronic effective mass and high carrier, GaInSb has a wide range of applications in the fields of optoelectronic devices, lasers and detectors due to its narrow band gap. This thesis is based on the growth process and theory of semiconductor materials, using modified vertical Bridgman method to grow the high quality of Gal-xInxSb (x=0.14) crystal ingot samples. The system analysis and detection of ingot samples by X ray diffraction, scanning electron microscopy and Hall effect testing system of professional testing instrument In this paper, we study the effects of multi crystal synthesis and crystal growth process (including the super heating temperature, growth rate and temperature gradient, etc.) on the microstructure and properties of ingot. The main conclusions are as follows:The following conclusions can be obtained in this paper:1 We produce the high quality Gal-xInxSb (x=0.14) crystal ingot successfully, the ingot size can be reach the diameter 11 mm, length up to 100mm.2 We research the effect of multi crystal synthesis process on the crystal structure and properties. The experimental results show that:We use the three form of synthesis (including Ga, Sb, In), in this scenario. The microstructure of the ingot is more uniform, the composition segregation is smaller, and the electrical properties and the physical properties are superior.3 We research the effect of the super heating temperature on the microstructure and properties of the crystal ingot. In the process of crystal growth, with increase of the superheat temperature, the viscosity of the melt would reduce, the growth interface is more stable, the ingot quality higher and higher. When the super heating temperature is 150oC, the dislocation density of GaInSb crystal is low, the microstructure defects are few, and the quality of ingot is high.4 We research the effect of the crystal growth rate (or the rate of moving crucible) on the microstructure and properties of the crystal ingot. When the crucible moving rate is too slow, the crystal grain size is small, and the composition segregation degree is bigger; however, crucible movement speed is too fast resulting in the crystal surface not stable, crystal structure interface not uniform, prone to twinning, thereby reducing the ingot quality. When the growth rate is 1-2 mm/h, sgregation of In element is small, homogeneous microstructure, electrical properties and physics experiments have reached the expected value.5 We research the effect of temperature gradient inside the furnace on the microstructure and properties of the crystal ingot. When the temperature gradient is small in the crystal growth process, the crystal potential is larger, and the nucleation is more difficult; however, if the temperature gradient is larger, the crystal will appear larger stress, the control to the crystal quality disadvantage. The experimental results show that in the temperature gradient is PCR=1 oC/mm, the ingot segregation degree is small, uniform structure, high quality ingot In addition, the experimental results obtained by the carrier mobility and resistivity value can be achieved in the commercial use of the standard.