Comparison of activation behavior of Cs-O and Cs-NF3-adsorbed GaAs(1 0 0)-β2(2 × 4) surface: From DFT simulation to experiment

Comparison Study of Structural Stability and Optoelectronic Properties of Al0.5Ga0.5N Thin Film and Nanowire Photocathode Surfaces under Different Activation Methods

“…This is due to the fact that an increase in Cs coverage enhances repulsive forces between Cs-adsorbed atoms, resulting in the activation system becoming increasingly unstable. This phenomenon is consistent with the adsorption energy trends of the Cs–NF 3 -adsorbed GaAs(100) – β 2 (2 × 4) surface from Li et al and the Cs/NF 3 coactivated In 0.53 Ga 0.47 As (001) surface from Fang et al with different Cs coverage. Furthermore, we can also find that the surface of Cs/NF 3 -activated Al 0.5 Ga 0.5 N thin films has lower adsorption energy than nanowire surface, which implies that Cs/NF 3 -activated thin films are more stable and their surface is more easily activated by Cs/NF 3 .…”

“…Also, the amount of adsorbed O atom and NF 3 molecule is all one. O atom, NF 3 module, and Li atoms tend to be adsorbed between the Cs atoms and the surface. ,, The adsorption energy of Al 0.5 Ga 0.5 N after activation is calculated separately by Formulas – and is depicted in Figure . The results show that, for Al 0.5 Ga 0.5 N thin films, the Cs/NF 3 -activated surface is the most stable, while the least stable is the Cs/NF 3 /Li-activated surface.…”

“…To investigate the stability of the Al 0.5 Ga 0.5 N photocathode after activation, we calculate the adsorption energy of the activated Al 0.5 Ga 0.5 N surface by different activation methods. The calculation formulas are ,, E normala normald normals normalC normals = E C s : normalA normall 0.5 normalG normala 0.5 normalN − E normalA normall 0.5 normalG normala 0.5 normalN − n μ normalC normals n E normala normald normals C s / O = E C s / normalO : normalA normall 0.5 normalG normala 0.5 normalN − E normalA normall 0.5 normalG normala 0.5 normalN − n μ normalC normals − m μ O n + m E normala normald normals C s / normalN F 3 = E …”

“…To investigate the stability of the Al 0.5 Ga 0.5 N photocathode after activation, we calculate the adsorption energy of the activated Al 0.5 Ga 0.5 N surface by different activation methods. The calculation formulas are ,, …”

“…Norton et al have achieved 32% quantum efficiency of Cs/O-activated NEA GaN photocathodes at 254 nm. For the surface activation method of III–V semiconductors, the coadsorption of Cs and NF 3 also achieves NEA surfaces. , Chanlek et al . have compared the decline in quantum efficiency of Cs/O-activated and Cs/NF 3 -activated surfaces of photoelectric emitting materials when exposed to impurity gases.…”