Effects Of Thermal Annealing On Defects And Electrical Properties In Large Diameter LEC SI-GaAs

GaAs is a compound semiconductor which has the best development in semiconductor materials, which is used to fabricate the devices and circuits of high frequency and speed because of its high mobility ratio and direct transition energy band structure. SI-GaAs have expansive market demand .The correlation devices have been used to light communication and secondary planet communication and so on. Because the growth technology and quality improvement of single crystal influence the devices development, so it is important that the single crystal diameter to get to be enlarged, the defects to be decreased for the the physical parameters and quality uniformity to be improved. So the investigation of detects and effects of thermal annealing on defects and the electrical properties of large diameter SI-GaAs are very important.In this paper, the distribution, pattern and density of detects in 6-inch SI-GaAs were investigated by mean of chemical etching and microscopy observation, etc. The detects were displayed by mean of AB etching; The samples after etching were checked and observed by metalloscope and scanning electron microscope and so on, the different pattern dislocations and microdefects were found. The radial distribution of EL2 concentration and C concentration was studied using infrared technique in detail. The electrical properties were measured by Hall system. The mechanics of thermal annealing effecting on EL2, As depositions and electrical parameters were investigated. The experimental results showed that there are cell structures, netted structures in the sample surface, and so on. The distribution of dislocation density and C concentration are W shape on sample diameter. The distribution of EL2 concentration is relatively lower in the center and higher on the edge of the wafer along the radial direction of as-grown samples. The distribution of EL2 concentration and As depositions change after thermal annealing. And the electrical parameters also change with the thermal annealing, which are due to the evaporation of As and the out-diffusion of As interstitial atoms. The conclusions are very useful for the producers of material and device to understand the effects of defects on the quality of devices and materials and concol the electrical parameters effectively.