XPS for probing the dynamics of surface voltage and photovoltage in GaN

- Photo response of n- and p-GaN samples are recorded by XPS using the Snapshot Mode with 0.1 s time resolution, and also under square wave electrical (SQW) pulses.
- Extent and dynamics of surface voltage and photovoltage are examined in the microseconds to seconds range.
- It is observed that for the p-GaN charging/discharging processes have multiple components with time constants of microseconds to seconds.
- The otherwise overlapping Ga3d peaks of the composite sample containing both n- and p-GaN are split into two distinct components of n- and p- separately.