Undoped Al0.48In0.52As grown by metalorganic chemical vapor deposition as the current-blocking layer of laser diodes

We have investigated the feasibility of using undoped Al0.48In0.52 As layers grown by low-pressure metalorganic chemical vapor deposition as current-blocking layers in buried-hetrostructure laser diodes. A high resistivity of over 2 × 1010 Ω · cm has been successfully obtained for a multi-layer structure of p-InP/n-InP/AlInAs/n-InP, when an undoped AlInAs layer was grown at a low growth temperature of 500°C. It has also been confirmed that no deposition of an AlInAs polycrystal occurs on the SiO2 mask at this low growth temperature. This multi-layer structure involving an undoped semi-insulating AlInAs layer has been applied to an InGaAsInGaAsP multi-quantum-well laser diode as a current-blocking structure. A CW threshold current of 8 mA and a slope efficiency of 0.11 mW/mA at room temperature, which are comparable to those of lasers having a conventional Fe-doped InP embedding layer as the current-blocking layer, have been achieved.