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市面上一般有三种材料可作为衬底:蓝宝石(A12O3)、硅(Si)、碳化硅(Sic)。其中蓝宝石是使用最多的衬底材料,具有生产技术成熟、器件质量较好、稳定性好、机械强度高、易于处理和清洗等优点。但是它也有许多不能克服的缺点:第一,晶格失配和热应力失配会导致外延层中产生大量缺陷,同时给后续的器件加工工艺造成困难;第二,蓝宝石是绝缘体,电阻率很大,无法制成垂直结构的器件;第三,通常只在外延层上表面制作N型和P型电极,造成了有效发光面积
There are generally three kinds of materials available on the market as substrates: sapphire (A12O3), silicon (Si), silicon carbide (Sic). Among them, sapphire is the most used substrate material, with the advantages of mature production technology, good device quality, good stability, high mechanical strength, easy handling and cleaning. But it also has many insurmountable disadvantages. First, lattice mismatch and thermal stress mismatch can lead to a large number of defects in the epitaxial layer and cause difficulties in subsequent device processing. Second, sapphire is an insulator with a very high resistivity Large, can not be made vertical structure of the device; Third, usually only in the epitaxial layer on the surface of the N-type and P-type electrode, resulting in an effective light-emitting area