| In this thesis, we focus on the growth of high-quality, large size, high materialutilization rate sapphire crystal and analysed its application performance on the LEDchip. We not only test the quality of the crystal by using a variety of instruments, butalso send them to an epitaxial manufacturer to make LED chips after processing thecrystal into wafers. According to the electrical property data, we finish its overallquality tracking. Specific content is as follows:1. Use heat exchanger method which is suitable for large size crystal growth togrow sapphire single crystal, and a c-axis alumina single crystal is used as seed toinduce the crystal growth. Two sapphire crystals were grown in this experiment, thefirst one has many cracks on it because of the improper annealing and cooling downprocess, and through regulate the annealing process and cooling rate, we get thesecond one as a sizeΦ170mm×160mm, weight12.15kg crystal after all, and thequality of the second one is good. The material utilization rate get to54%when weprocess the second crystal into ingot, much higher than material utilization ratecrystal grown by traditional a-axis kyropoulos method.2. One of the main applications of sapphire crystal is to be substrate material forLED, so after epitaxial process, the wafers which used for experiment were made intoLED chips, and contrast analysis were made between the LED chips made by series Awafers which have relatively large internal stress and series B wafers which haverelatively small internal stress, experiment wafers and production wafers. Accordingto the electrical property data, we know the luminous intensity of LED chips made byexperiment wafers is higher than production wafers, and the reliability of LED chipsmade by series B wafers is better than series A wafers.Energy-saving and emission-reducing are vigorously advocated today, LED ismore widespread used in indicating lamp, display, backlight, general lighting andother fields, so as to promote its mainstream substrate material—sapphire’s largescale development, therefore, the research on the growth technology of high-quality,large size, high material utilization rate sapphire crystal is of great significance, andis worth to pay more attention on it. |
