Formation of luminescent centers in GaN powders by the two-stage vapor phase synthesis and their phosphor application

1.系统地研究了未掺杂氮化镓粉末在颗粒生长阶段的气体组成、GaCl、NH_3和H_2及其分压。基于这些结果，样品的发光性能得到了显著的改善。采用两段气相法，以ZnS粉末为源，进行颗粒生长，制备了GaN:Zn粉末。通过选择载气（n2或HCl）及其流速控制ZnS的供给速率，使Zn浓度在1×10^<19> ~ 8×10^<20> cm^<-3>之间得到广泛控制。结果发现，样品中还掺入了与Zn浓度几乎相同的S。合成的GaN:Zn粉末呈现蓝色光致发光和阴极发光。光谱由位于450 nm左右的宽发射带组成。对锌浓度对发射特性的影响进行了系统表征。研究发现，在GaN:Zn粉末的生长阶段，其发光强度与NH_3的分压密切相关。随着分压的增加，排放强度逐渐增大，达到0.78大气压。用Zn金属代替ZnS作为源，可以显著改善样品的发光和结晶性能，这表明S的加入对样品的质量有负面影响。

1.The characterization of undoped GaN powders on the constituent of gases, GaCl,NH_3 and H_2, and their partial pressures at the stage of particle growth was carried out systematically. Based on these results, the dramatic improvement in the luminescent property of the samples has been achieved.2.The synthesis of GaN:Zn powders by the two-stage vapor phase method, in which a ZnS powder was used as a source for the stage of particle growth. The supply rate of ZnS was controlled by choice of carrier gas (N_2 or HCl) and their flow rate, which enabled the extensive control of Zn concentration between 1×10^<19>〜8×10^<20> cm^<-3>. It was found that S of almost the same concentration as Zn was also incorporated in the samples.3.The synthesized GaN:Zn powder showed blue photomminescence and cathodeluminescence. The spectra consisted of a broad emission band located around 450 nm. The emission was characterized systematically on the Zn concentration.4.It was found that the luminescence from the GaN:Zn powder is dependent strongly on the partial pressure of NH_3 at the stage of particle growth. The emission intensity increased with increasing the partial pressure in the region up to 0.78 atm.5.The dramatic improvement in the luminescence and crystalline properties has been achieved by using Zn metal as a source instead of ZnS, which suggests that the incorporation of S has a negative effect on the quality of samples.