Rapid thermal redistribution of copper impurities in GaAs_xP_1-x at temperatures above 250 °C

Abstract

Light emitting GaAs_xP_1-x diodes with As concentrations below x = 0.6 have been Cu-doped and life-tested. Beside strongly decreased efficiencies, tested diodes exhibit deteriorated, i. e. soft reverse voltage characteristics related to microplasma formation. The sites where microplasmas are formed are dislocations penetrating the p-n junction. Heat treatment for 25 min at temperatures as low as 250 °C strongly improves the reverse voltage characteristic. Full recovery of the original characteristic may be established at 300 °C within about 2 hours. The heat treatment causes the microplasmas to disappear completely, the original optical efficiency, however, is not regained. The cycle: optical testing, heat treatment with the recovery of the electrical characteristic, optical testing, etc. can be repeated many times. During this cycling the microplasmas of diffused diodes change from a distribution evenly spread over the dislocations of the diffused area into a narrow ring close to the edge of the diffusion window.