Photoemission from activated gallium arsenide. I. Very-high-resolution energy distribution curves.
Photoemission from activated gallium arsenide. I. Very-high-resolution energy distribution curves.
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DOI：
10.1103/physrevb.31.3859
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发表时间：
1985-03
期刊：
影响因子：
--
通讯作者：
Drouhin;Hermann;Lampel
中科院分区：
文献类型：
--
作者：
Drouhin;Hermann;Lampel
研究了在超高真空条件下激活负电子亲和势的 p 型掺杂 (∼ 10 19 cm− 3) GaAs 晶体的 (100) 面发射的光电子的能量分布曲线 (EDC)。该研究是在 300 和 120 K、聚焦良好的 Kr+ 激光激发下进行的，具有非常高的能量分辨率 (20 meV)。对 EDC 作为光子能量函数的分析（主要是在低温下）提供了远离布里渊区中心的 GaAs 能带结构的非常直接的图像。实验结果通过耦合导带和价带的球形、非抛物线 k→⋅ p→ 微扰计算得到了很好的拟合，中心 Γ 谷的电子动能高达 1 eV。辅助 L 和 X 最小值在能量弛豫和光电子发射过程中发挥的重要作用得到了证明。对总发射电流的主要贡献是由于电子在发射到真空之前在体 Γ 最小值处被热化并且在能带弯曲区域中损失了平均能量≃ 130 meV。显示带弯曲值≥ 0.5 eV。讨论了砷化镓光电阴极的产率和时间演化。这项详细的研究导致了对 LW James 和 JL Moll [Phys. Rev. 183, 740 (1969)] 并很好地理解了活化 GaAs 的光电发射特性。
The energy distribution curves (EDC’s) of the photoelectrons emitted from the (100) face of a p-type doped (∼ 10 19 cm− 3) GaAs crystal, activated to negative electron affinity in ultrahigh-vacuum conditions, is investigated. The study is performed at 300 and 120 K under well-focused Kr+-laser excitation and with a very-high-energy resolution (20 meV). The analysis of the EDC’s as a function of the photon energy, mainly at low temperature, is shown to provide a very direct picture of the GaAs band structure away from the Brillouin-zone center. The experimental results are well fitted by a spherical, nonparabolic k→⋅ p→ perturbation calculation of the coupled conduction and valence bands, for electron kinetic energies up to 1 eV in the central Γ valley. The essential role played by the subsidiary L and X minima in the energy relaxation and photoemission processes is evidenced. The main contribution to the total emitted current is due to electrons which were thermalized in the bulk Γ minimum and have lost an average energy≃ 130 meV in the band-bending region prior to emission into vacuum. The band-bending value is shown to be≥ 0.5 eV. The yield and time evolution of GaAs photocathodes are discussed. This detailed study leads to a reexamination of the pioneer work of LW James and JL Moll [Phys. Rev. 183, 740 (1969)] and to a good understanding of the photoemission properties of activated GaAs.