The transient photoresponse was analysed using two different setups. First, at a Lake Shore Cryotronics CRX-6.5K probe station, described in more detail in our previous work, and second, on a custom built confocal microscope to enable diffraction limited illumination, cf. Figure for more details. In short, laser illumination was carried out with either a square pulse laser for the steady state response or a pico-second pulsed laser for the non-steady state response. A Hewlett Packard 33120A arbitrary waveform generator was used in combination with a fast-switching laser driver (FSL500, PicoQuant) and a 635 nm laser diode. The laser had a nominal laser switching time of less than 0.5 ns and an output power of approximately 2 mW at the fibre. The Taiko PDL M1 (PicoQuant) picosecond pulsed laser driver was employed with a 636 nm laser head having a pulse width <500 ps and an average output power of 81 µW at a repetition frequency of 1 MHz.