Doping is essential in the growth of bulk GaN substrates,which could help control the electrical properties to meet the requirements of various types of GaN-based devices.The progresses in the growth of undoped,Si-dop...Doping is essential in the growth of bulk GaN substrates,which could help control the electrical properties to meet the requirements of various types of GaN-based devices.The progresses in the growth of undoped,Si-doped,Ge-doped,Fedoped,and highly pure GaN by hydride vapor phase epitaxy(HVPE) are reviewed in this article.The growth technology and precursors of each type of doping are introduced.Besides,the influence of doping on the optical and electrical properties of GaN are presented in detail.Furthermore,the problems caused by doping,as well as the methods to solve them are also discussed.At last,highly pure GaN is briefly introduced,which points out a new way to realize high-purity semi-insulating(HPSI) GaN.展开更多
In this paper we investigated the optical properties of ZnO and Mn doped ZnO nanocrystals that were fabricated by a vapor phase transport growth process, using zinc acetate dihydrate with or without Mn in a constant O...In this paper we investigated the optical properties of ZnO and Mn doped ZnO nanocrystals that were fabricated by a vapor phase transport growth process, using zinc acetate dihydrate with or without Mn in a constant O2/Ar mixture gas flowing through the furnace at 400600℃, respectively. The as grown ZnO nanocrystals are homogeneous with a mean size of 19 nm observed by scanning electron microscope（SEM）. The optical characteristics were analyzed by absorption spectra and photoluminescence（PL） spectra at room-temperature. For ZnO nanocrystals, a strong and predominant UV emission peaked at 377 nm was found in the PL spectra. For Mn doped ZnO nanocrystals, in addition to the strong UV emission, a strong blue emission peaked at 435 nm was observed as well. By doping Mn ions, the major UV emission shifts from 377 nm to 408 nm, showing that Mn ions were not only incorporated into ZnO Ncs, but also introduced an impurity level in the bandgap. Moreover, with the concentration of Mn increasing, the relative intensities of the two emissions change largely, and the photoluminescence mechanism of them is discussed.展开更多
A new type of Sm-Co supersaturated solid solution has been developed with a stabilized TbCu7-type structure. The high-Co single phases were stabilized in a wide temperature range in the prepared SmCo9.8.xSix(x=0–0.9)...A new type of Sm-Co supersaturated solid solution has been developed with a stabilized TbCu7-type structure. The high-Co single phases were stabilized in a wide temperature range in the prepared SmCo9.8.xSix(x=0–0.9) alloys by concurrent nanostructuring and Si-doping. The significant enhancement of the coercivity and remanence of the new type supersaturated solid solution are attributed to the effective pinning of the ultrafine nanograin boundaries and the high magnetocrystalline anisotropy of the solid solution. It was proposed that the high-temperature magnetic properties of the Sm-Co supersaturated solid solution depend strongly on the phase stability.展开更多
通过气相外延技术生长了Au掺杂的Hg_(1-x)Cd_xTe薄膜材料。利用傅里叶光谱仪和金相显微镜对外延材料进行了表征。通过二次离子质谱(Secondary Ion Mass Spectroscopy,SIMS)技术分析了Au在Hg_(1-x)Cd_xTe外延层以及CdZnTe衬底中的纵向分...通过气相外延技术生长了Au掺杂的Hg_(1-x)Cd_xTe薄膜材料。利用傅里叶光谱仪和金相显微镜对外延材料进行了表征。通过二次离子质谱(Secondary Ion Mass Spectroscopy,SIMS)技术分析了Au在Hg_(1-x)Cd_xTe外延层以及CdZnTe衬底中的纵向分布趋势。利用SIMS技术还分析了Ⅰ、Ⅱ族和Ⅵ、Ⅶ族杂质在Hg_(1-x)Cd_xTe外延层以及CdZnTe衬底中的纵向分布趋势,发现衬底和外延层的过渡区具有吸杂作用。研究结果对提高探测器的性能具有指导意义。展开更多
基金Project supported by the National Key Research and Development Program of China(Grant Nos.2017YFB0404100 and 2016YFA0201101)the National Natural Science Foundation of China(Grant Nos.61574164,61704187,and 61604170)+2 种基金the Key Research Program of the Frontier Science of the Chinese Academy of Sciences(Grant No.QYZDB-SSW-SLH042)the State Key Program of the National Natural Science Foundation of China(Grant Nos.61734008and 11435010)the National Key Scientific Instrument and Equipment Development Project,China(Grant No.11327804)。
文摘Doping is essential in the growth of bulk GaN substrates,which could help control the electrical properties to meet the requirements of various types of GaN-based devices.The progresses in the growth of undoped,Si-doped,Ge-doped,Fedoped,and highly pure GaN by hydride vapor phase epitaxy(HVPE) are reviewed in this article.The growth technology and precursors of each type of doping are introduced.Besides,the influence of doping on the optical and electrical properties of GaN are presented in detail.Furthermore,the problems caused by doping,as well as the methods to solve them are also discussed.At last,highly pure GaN is briefly introduced,which points out a new way to realize high-purity semi-insulating(HPSI) GaN.
基金supported in parts by the National Natural Science Foundation of China(No.60776004,60976071)the Laboratory for Thin Film Microfabrication of the Ministry of Education
文摘In this paper we investigated the optical properties of ZnO and Mn doped ZnO nanocrystals that were fabricated by a vapor phase transport growth process, using zinc acetate dihydrate with or without Mn in a constant O2/Ar mixture gas flowing through the furnace at 400600℃, respectively. The as grown ZnO nanocrystals are homogeneous with a mean size of 19 nm observed by scanning electron microscope（SEM）. The optical characteristics were analyzed by absorption spectra and photoluminescence（PL） spectra at room-temperature. For ZnO nanocrystals, a strong and predominant UV emission peaked at 377 nm was found in the PL spectra. For Mn doped ZnO nanocrystals, in addition to the strong UV emission, a strong blue emission peaked at 435 nm was observed as well. By doping Mn ions, the major UV emission shifts from 377 nm to 408 nm, showing that Mn ions were not only incorporated into ZnO Ncs, but also introduced an impurity level in the bandgap. Moreover, with the concentration of Mn increasing, the relative intensities of the two emissions change largely, and the photoluminescence mechanism of them is discussed.
基金supported by the National Key Program of Research and Development(Grant No.2016YFB0700503)the National Natural Science Foundation of China(Grant No.51371012)the National Science Fund for Distinguished Young Scholars(Grant No.51425101)
文摘A new type of Sm-Co supersaturated solid solution has been developed with a stabilized TbCu7-type structure. The high-Co single phases were stabilized in a wide temperature range in the prepared SmCo9.8.xSix(x=0–0.9) alloys by concurrent nanostructuring and Si-doping. The significant enhancement of the coercivity and remanence of the new type supersaturated solid solution are attributed to the effective pinning of the ultrafine nanograin boundaries and the high magnetocrystalline anisotropy of the solid solution. It was proposed that the high-temperature magnetic properties of the Sm-Co supersaturated solid solution depend strongly on the phase stability.
文摘通过气相外延技术生长了Au掺杂的Hg_(1-x)Cd_xTe薄膜材料。利用傅里叶光谱仪和金相显微镜对外延材料进行了表征。通过二次离子质谱(Secondary Ion Mass Spectroscopy,SIMS)技术分析了Au在Hg_(1-x)Cd_xTe外延层以及CdZnTe衬底中的纵向分布趋势。利用SIMS技术还分析了Ⅰ、Ⅱ族和Ⅵ、Ⅶ族杂质在Hg_(1-x)Cd_xTe外延层以及CdZnTe衬底中的纵向分布趋势,发现衬底和外延层的过渡区具有吸杂作用。研究结果对提高探测器的性能具有指导意义。
