Novel Cladding Structure for ZnSe-based White Light Emitting Diodes with Longer Lifetimes of over 10,000 h

We have demonstrated ZnSe-based white light emitting diodes (LEDs) with longer lifetimes of over 10,000 h at 14.5 A/cm 2 by introducing an i-ZnMgBeSe/p-ZnMgSe double cladding structure, which includes a very thin i-ZnMgBeSe layer for suppressing electron overflow and a p-ZnMgSSe layer for efficient p-type carrier concentration. By adopting the double cladding layer instead of only the conventional p-ZnMgSSe cladding layer, rapid degradation is suppressed and the lifetime tendency becomes similar to that of the LEDs consisting of a III–V semiconductor system. The device simulation and the temperature dependence of optical power showed that the i-ZnMgBeSe layer played the main role in increasing electron confinement. Our experimental data and reliability test results indicate that the suppression of the electron overflow is essential to achieve a long lifetime acceptable for practical use.