Study on valence band and work function of n-type Hg3In2Te6 single crystal by photoelectron spectroscopy

• Te concentration increased and Hg concentration decreased with the increasing of etching voltage.
• There was the presence of a Te-rich surface after etching and the formation of Te islands happened during etching process.
• The work function of MIT wafer did not change greatly with the voltage increasing from 1 kV to 4 kV.
• The ideal Ar+ ion etching voltage of MIT wafer was from 0.5 kV to 1 kV.

Photoelectron spectroscopy was used to study the valence band and work function of n-type Hg3In2Te6 (short for MIT) single crystal under different Ar+ ion etching process. It is found that Te and Hg concentration on the surface of MIT increased and decreased with the increasing of etching voltage respectively. Meanwhile, the surface work function increased from 4.23 eV to 4.63 eV after etching for 1 min under the voltage about 0.5 kV, which was mainly caused by the removal of O atoms from Te–O bond. This will lead to increase of surface dangling bonds and pin the Fermi level. With the increasing of etching voltage from 0.5 kV to 4 kV, the work function slowly increased. This phenomenon could be explained by the atoms reconstruction and the formation of Te clusters on the surface of MIT.