The sensor surface is completely flat, no structures, wiring or passivation are required.
At the same time, the "light-addressability" of the LAPS makes it possible to obtain a spatially resolved map of the distribution of the ion concentration in the specimen.
The spatial resolution of the LAPS is an important factor and is determined by the beam size and the lateral diffusion of photocarries in the semiconductor substrate.
By illuminating parts of the semiconductor surface, electron-hole pairs are generated and a photocurrent flows.
Under a fixed bias voltage, the AC (kHz range) photocurrent signal varies depending on the solution.