Reliability of vapor-grown InGaAs and InGaAsP heterojunction laser structures

The reliabilities of vapor-grown ternary InGaAs/InGaP and quaternary InGaAsP/InP heterojunction structures have been compared. Quaternary structures have been found to have much longer operating lives than ternary structures, with InGaAsP heterojunction LED´s having attained over 9000 h of operation to date at 60°C. Room-temperature CW operation of 1.25 μm InGaAsP/InP lasers also has been obtained for 4500 h, to date, without appreciable degradation. Lattice mismatch has been found to strongly limit the operating life of hereto-junction diodes, even though it does not affect initial device performance. Several device processing techniques were evaluated to determine their effect on device reliability. The use of oxide-defined stripe contacts (rather than broad-area contacts), cleaved (rather than polished) facets, and Al2O3-coated (rather than uncoated) facets all were found to enhance device reliability.