Improved 634 nm MQW AlGaInP LEDs Performance with Novel Tensile Strain Barrier Reducing Layer

Abstract

Light-emitting diodes (LEDs) under long-term or high-current operating undergo significant performance change and degradation with time. Thus a novel GaxIn1-xP tensile strain barrier reducing (TSBR) structure is grown between window and cladding layers of multi- quantum-well-AlGaInP LEDs. The TSBR (∼150 ÅGaxIn 1-xP) film is of lattice size and valence band energy intermediate between those of window and cladding layers, thus reducing band offset. Experimental characterization shows significant decrease in device forward bias, dynamic resistance and junction heating, with strong improvement in power output degradation for the high current region. Various compositions of Ga xIn1-xP TSBR are fabricated, aged at dc 50 mA, and tested at nonradiative and radiative current levels. Optimal GaxIn 1-xP composition is determined. Two separate power output degradation mechanisms are noted and discussed. In sum, the TSBR layer appears a highly successful design for improved power efficiency, reliability and global lifetime behavior of an LED-type device.