Study of degradation of diode structures by the use of probes

Abstract

Using structures with probes the possibility is shown to obtain an important information about the degradation changes in different regions of a light emitting diodes (LED) as well as to study the effect of the potential barrier of the p‐n junction on the degradation processes. The direct experiments on the structures with probes show that the degradation of GaP:N LED's are due to the processes in the p++‐layer adjacent to the Ohmic contact or to the processes in the Ohmic contact itself. These processes are likely to be connected with the minority carriers.

Probe Method for Studying Noise in Diode Structures and Its Implementation in GaP:N Light-Emitting Diodes

“…Fig. 3 (curves 2 and 2') presents the Sp-n(Up-n) curves before and after the degradation, respectively (Up-,, is the voltage across the p-n junction) as well as the I-U characteristics of the p-n junction before and after the degradation (curves 1 and l'), measured by the probe technique [4]. As seen, in the process of degradation the level of recombination current I , increases and the SF-" noise level decreases, while the values of the diffusion component of the current, Idif (obtained by resolving the I-U characteristic of the p-n junction), remain unchanged (curve 3).…”

“…To find them, an audio-frequency current is passed through the probe structure (contacts 1 -2) and resistance R,(R, % rd) and distribution of the alternating voltage between these contacts is measured. The current noise sources sought for are determined from Note that apart from the possibility of monitoring the noise characteristics of every diode region, the probe diode structure offers another important advantage, namely, makes it possible to measure the I -U characteristics of the regions, the brightness-voltage characteristic of the p-n junction, and thereby to monitor degradation phenomena in the diode structure [4].…”