The addition reactions of alkenes and alkynes to the H-terminated GaN （0001） surface with a Ga dangling-bond have been studied employing periodic density functional theory （PDFT） calculations. Detailed information...The addition reactions of alkenes and alkynes to the H-terminated GaN （0001） surface with a Ga dangling-bond have been studied employing periodic density functional theory （PDFT） calculations. Detailed information on the reaction pathways of these alkenes and alkynes with H-GaN （0001） surface is provided, which indicates that the reactions contain two steps separated by the metastable intermediates： elementary addition reaction and H-abstraction process. From the energy curves, the reactions are clearly viable in the cases of ethene, styrene and phenylacetylene; while for ethyne, the H-abstraction barrier is higher than the desorption barrier of the intermediate, so the adsorbed C2H2 in intermediate is more likely to be desorbed back into the gas phase than to form a stable adsorbed species. Furthermore, it is obvious that for either alkenes or alkynes, the systems substituted by phenyl have more stable intermediates because π conjugation could improve their stabilities.展开更多
采用热壁化学气相沉积工艺在 Si(111)衬底上生长 GaN 晶体膜,并对其生长条件进行研究。用 X 射线衍射(XRD)、扫描电镜(SEM)、荧光光谱(PL)对样品进行结构、形貌和发光特性的分析。测试结果表明:用此方法得到了六方纤锌矿结构的 GaN 晶...采用热壁化学气相沉积工艺在 Si(111)衬底上生长 GaN 晶体膜,并对其生长条件进行研究。用 X 射线衍射(XRD)、扫描电镜(SEM)、荧光光谱(PL)对样品进行结构、形貌和发光特性的分析。测试结果表明:用此方法得到了六方纤锌矿结构的 GaN 晶体膜。实验结果显示:采用该工艺制备 GaN 晶体膜时,选择 H2 作反应气体兼载体,对 GaN 膜的形成起着非常有利的作用。展开更多
In this work, we study the influence of carrier gas H2flow rate on the quality of p-type GaN grown and annealed at lower temperatures. It is found that the concentration of H atoms in Mg-doped GaN epilayer can effecti...In this work, we study the influence of carrier gas H2flow rate on the quality of p-type GaN grown and annealed at lower temperatures. It is found that the concentration of H atoms in Mg-doped GaN epilayer can effectively decrease with appropriately reducing the carrier gas H2flow rate, and a high-quality p-type GaN layer could be obtained at a comparatively low annealing temperature by reducing the carrier gas H2flow rate. Meanwhile, it is found that the intensity and wavelength of DAP peak are changed as the annealing temperature varies, which shows that the thermal annealing has a remarkable effect not only on the activation of acceptors but also on the compensation donors.展开更多
基金Supported by the National Natural Science Foundation of China (No 20673019)
文摘The addition reactions of alkenes and alkynes to the H-terminated GaN （0001） surface with a Ga dangling-bond have been studied employing periodic density functional theory （PDFT） calculations. Detailed information on the reaction pathways of these alkenes and alkynes with H-GaN （0001） surface is provided, which indicates that the reactions contain two steps separated by the metastable intermediates： elementary addition reaction and H-abstraction process. From the energy curves, the reactions are clearly viable in the cases of ethene, styrene and phenylacetylene; while for ethyne, the H-abstraction barrier is higher than the desorption barrier of the intermediate, so the adsorbed C2H2 in intermediate is more likely to be desorbed back into the gas phase than to form a stable adsorbed species. Furthermore, it is obvious that for either alkenes or alkynes, the systems substituted by phenyl have more stable intermediates because π conjugation could improve their stabilities.
文摘采用热壁化学气相沉积工艺在 Si(111)衬底上生长 GaN 晶体膜,并对其生长条件进行研究。用 X 射线衍射(XRD)、扫描电镜(SEM)、荧光光谱(PL)对样品进行结构、形貌和发光特性的分析。测试结果表明:用此方法得到了六方纤锌矿结构的 GaN 晶体膜。实验结果显示:采用该工艺制备 GaN 晶体膜时,选择 H2 作反应气体兼载体,对 GaN 膜的形成起着非常有利的作用。
基金Project supported by the the Science Challenge Project of China(Grant No.TZ2016003)the National Natural Science Foundation of China(Grant Nos.61674138,61674139,61604145,61574135,61574134,61474142,and 61474110)Beijing Municipal Science and Technology Project(Grant No.Z161100002116037)
文摘In this work, we study the influence of carrier gas H2flow rate on the quality of p-type GaN grown and annealed at lower temperatures. It is found that the concentration of H atoms in Mg-doped GaN epilayer can effectively decrease with appropriately reducing the carrier gas H2flow rate, and a high-quality p-type GaN layer could be obtained at a comparatively low annealing temperature by reducing the carrier gas H2flow rate. Meanwhile, it is found that the intensity and wavelength of DAP peak are changed as the annealing temperature varies, which shows that the thermal annealing has a remarkable effect not only on the activation of acceptors but also on the compensation donors.
