A technique for the investigation of deep-level states in diffused p—N junction devices: Application to GaAs electroluminescent diodes

Analytical equations describing the high-frequency (1 MHz) capacitance-voltage ( ) characteristics have been derived for diffused p-n junction diodes, including the effect of deep-level states within the bandgap. It was found that the C^-3versus curve becomes nonlinear when the density of the deep-level states is large. From the derived equation the density of the deep-level states may be calculated from the slope of the versus curve, where V2is related to the energy level of the deep states. The value of V2may be determined from the recombination current versus temperature measurements at small bias. The theory has been applied to characterize the dominant deep-level recombination centers in Zn-diffused GaAs light-emitting diodes. The measured deep levels are within 0.2 eV of the midgap energy and the density of these centers is of the order of 10¹⁶cm^-3.