Here q represents the elementary charge, ɛ represents the dielectric constant of the Sb2Se3 (taken as 15.1), 45 ɛ0 is the permittivity of free space, and A is the measured area of the diode. In the DLCP measurements, the carrier density is derived from the nonlinear relationship between the change in charges (δQ) and the perturbation AC bias (δV):