[20p-PB1-1~13] 6.5 Surface Physics, Vacuum

[20p-PB1-4] Properties of the microscopic surface states and the electron emission

〇Ryutaro Fukuzoe¹, Masayuki Hirao¹, Erika Tanaka¹, Takashi Meguro¹ (1.Tokyo Univ. of Sci.)

Keywords:photocathode, gallium arsenide, scanning tunneling microscopy

The negative electron affinity (NEA) surface receives low energy nearly equal to the band gap energy of a semiconductor to emit an electron because this lowers the vacuum level than the conduction band minimum. In particular NEA-GaAs surfaces show distinct characteristics such as high spin polarization, low emittance, short pulse availability, and high intensity. NEA surfaces are made by adding Cs and oxygen alternatingly onto the clean surface of GaAs. Scanning tunneling microscopy (STM) is used to investigate surface morphology of the GaAs (100) surfaces prepared by the HCl-isopropanol (HCl-iPA) treatment and annealing in ultrahigh vacuum (UHV). The method indicates improvement in surface quality of the GaAs (100).