THE SMALL-SIGNAL AC IMPEDANCE OF GALLIUM-ARSENIDE AND SILICON P-I-N-DIODES

The purpose of this paper is to demonstrate that the impedance of the p-i-n diode is definable as a function of frequency and depends on the diode's geometry and electronic properties. The impedance analysis includes the effects of different electron and hole mobilities, making the model suitable for modeling the a.c. impedance of both silicon and gallium arsenide -i-n diodes. The small signal model shows that for frequencies near the inverse of the intrinsic region carrier lifetime, the diode shows either capacitive or inductive reactance, depending on its geometry. The analysis also indicates that p-i-n diodes with certain combinations of geometry and carrier lifetime show a nearly constant resistance and negligible reactance at all frequencies. At high frequencies for p-i-n diodes of any geometry, the reactive component essentially disappears and the impedance is purely resistive. The series equivalent p-i-n diode impedance model is compared with measured impedance vs frequency data for both silicon and gallium arsenide -i-n diodes. © 1990.