  Capacitance-Voltage (CV) measurements along with the Mott-Schottky (MS)
analysis are widely used for characterization of material and device
parameters. Using a simple analytical model, supported by detailed numerical
simulations, here we predict that the capacitance of thin film devices scale as
V^-2 (V is the applied potential), instead of the often used V^-0.5 dependence
of MS analysis- with significant implications towards extraction of parameters
like doping density, built-in voltage, etc. Surprisingly, we find that the
predicted trends are already hidden in multiple instances of existing
literature. As such, our results constitute a fundamental contribution to
semiconductor device physics and are directly applicable and immediately
relevant to a broad range of optoelectronic devices like organic solar cells,
perovskite-based solar cells, and LEDs, thin film a-Si devices, etc.
