Properties of violet laser diodes grown on bulk GaN substrates

摘要

High pressure grown GaN bulk crystals, because of their low defect density, are atractive for the use as substrates for blue-violet laser diode fabrication. These laser diodes are characterized by a low density of dislocations (8·10~4-1·10~5 cm~(-2) and thus they possibly have the best crystalline quality ever reported for this type of nitride devices. Previously, we demonstrated that these lasers are able to emit a very high optical power under pulse operation. In the present paper we will demonstrate the details of their room temperature CW operation, giving good prognostics for the further development of these devices. Preliminary estimation of the internal losses indicated a very low internal absorption in the range of 5 cm~(-1). The characterization of the aged devices did not reveal any dark lines or facet degradation. A correlation between the device lifetime and p-type layers growth methods will be suggested here.