Surface charging at the (1 0 0) surface of Cu doped and undoped Li2B4O7

We have compared the photovoltaic charging of the (1 0 0) surface termination for Cu doped and undoped Li2B4O7. While the surface charging at the (1 0 0) surface of Li2B4O7 is significantly greater than observed at (1 1 0) surface, the Cu doping plays a role in reducing the surface photovoltage effects. With Cu doping of Li2B4O7, the surface photovoltaic charging is much diminished at the (1 0 0) surface. The density of states observed with combined photoemission and inverse photoemission remains similar to that observed for the undoped material, except in the vicinity of the conduction band edge.

Graphical abstract.Download full-size imageResearch highlights▶ The Cu doping suppresses both the hysteresis in photovoltaic charging and the temperature at which surface charging ceases at the surface of lithium tetraborate, a pyroelectric material. ▶ There is either an increase in carrier concentration or carrier lifetimes with Cu doping.