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 (
C-V
) 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
^-3
versus
V
curve becomes nonlinear when the density of the deep-level states is large. From the derived
C-V
equation the density of the deep-level states may be calculated from the slope of the
C^{3}V
versus
C(V- V_{2})/V^{2}
curve, where V
2
is related to the energy level of the deep states. The value of V
2
may 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 10
¹⁶
cm
^-3
.