Proton bombardment formation of stripe-geometry heterostructure lasers for 300 ° K CW operation

A proton-bombardment method of preparing stripe geometry junction lasers is reported here, and the operating characteristics of these new devices are compared with the previously described oxide-insulated stripe geometry lasers. In a typical procedure, a slice containing an epitaxially grown heterostructure is bombarded with protons producing a high-resistivity layer 3 µm deep which penetrates through the active p-region of the device. The lasing region is masked from the protons by evaporated and photo-etched gold stripes 3µm thick. The device is then annealed at 450°C for 15 min. to remove the undesired bombardment-induced optical absorption while still retaining sufficiently high resistivity for current confinement. For a 12 µm wide strip, the resulting double heterostructure lasers have room temperature threshold currents which are typically a factor of two lower than the oxide-insulated lasers. Bombardment-insulated lasers have operated continuously on diamond heat sinks up to 110°C (heat sink temperature), often in the lowest order spatial mode. There appear to be no aging effects whicll can be attributed to bombardment.