DEHYDROGENATION AND THE SURFACE PHASE TRANSITION ON DIAMOND (111) : KINETICS AND ELECTRONIC STRUCTURE
DEHYDROGENATION AND THE SURFACE PHASE TRANSITION ON DIAMOND (111) : KINETICS AND ELECTRONIC STRUCTURE
复制标题
DOI：
10.1103/physrevb.59.5847
复制
发表时间：
1999-02
影响因子：
3.7
通讯作者：
J. Cui;J. Ristein;L. Ley
中科院分区：
文献类型：
--
作者：
J. Cui;J. Ristein;L. Ley
用芯能谱、低能电子衍射和电子亲合势测量研究了氢覆盖金刚石（111）表面的（1 × 1）到（2 × 1）表面相变。后一种方法被证明是一个可靠的措施的氢覆盖。在1000 K下延长表面退火将电子亲和势为-1.27 eV的氢封端（1 × 1）结构转变为无氢（2 × 1）重构结构，将价带最大值与费米能级EF的分离从0.68 eV增加到0.88 eV，并导致正电子亲和势为+0.38 eV。在高温（高达1400 K）下对表面进行退火，产生相同的（2 × 1）表面结构，尽管价带最大值与EF的间隔增加到1.42 eV，并且正电子亲和力为0.8 eV，这与部分石墨化有关。表面石墨化。热致氢解吸的动力学分析产生1.25 ± 0.2 eV的活化能。结果表明，氢的脱附和重构是表面相变，两者之间没有直接的联系。相反，观察到具有高浓度悬挂键（高达70%）的中间相。（1 × 1）到（2 × 1）的相变在现象学上可以用一级相变来描述，只要在分析中包含约70%的悬挂键临界密度，使得重构速率常数在低于该值时为零。
The (1× 1) to (2× 1) surface phase transition of the hydrogen-covered diamond (111) surface is investigated by core level spectroscopy, low-energy electron diffraction, and measurements of the electron affinity. The latter method is shown to be a reliable measure of the hydrogen coverage. Prolonged annealing of the surface at 1000 K converts the hydrogen-terminated (1× 1) structure with an electron affinity of-1.27 eV to a hydrogen-free (2× 1) reconstruction, increases the separation of valence-band maximum from the Fermi level E F from 0.68 to 0.88 eV, and results in a positive electron affinity of+ 0.38 eV. Annealing the surface at high temperature (up to 1400 K) yields the same (2× 1) surface structure albeit with an increase in the separation of the valence-band maximum from E F to 1.42 eV and a positive electron affinity of 0.8 eV which is associated with a partial surface graphitization. An analysis of the kinetics of the thermally induced hydrogen desorption yields an activation energy of 1.25±0.2 eV. It was found that hydrogen desorption and reconstruction are surface phase transitions which are not directly linked. Instead, an intermediate phase with a high concentration of dangling bonds (up to 70%) is observed. The (1× 1) to (2× 1) phase transition is phenomenologically well described by a first-order transition provided a critical density of dangling bonds of about 70% is included in the analysis in such a way that the rate constant for reconstruction vanishes below that value.