Si doping for n- and p-type conduction in AlxGa1−x As grown on GaAs(311)A by molecular-beam epitaxy

Abstract

For Si-doped AlxGa1−xAs(311)A with 0⩽x⩽1 grown by molecular-beam epitaxy, a systematic study of electrical properties is performed depending on growth conditions. A phase diagram for the conversion of the conduction type as a function of growth temperature and V/III beam-equivalent pressure ratio is established for AlxGa1−xAs layers. To achieve n-type conduction in AlxGa1−xAs layers, high arsenic flux and growth temperatures not exceeding about 550 °C are required, whereas low arsenic flux and higher growth temperatures lead to p-type conduction. For Si-doped AlxGa1−xAs(311)A layers with x>0.5, p-type conduction is reported with a Si doping efficiency above 90%. Based on these results, all-Si-doped strained-layer In0.2Ga0.8 As/GaAs(311)A quantum-well laser structures with x=0.5 and 0.8 in the cladding layers were grown. Compared with reference laser structures grown on GaAs(100) and doped with Be, a better lasing performance of the all-Si-doped (311)A-oriented single quantum-well laser structures is obtained. For 1.5 mm long conventional broad area lasers, we achieve a lower threshold current density (280 A/cm2), an internal quantum efficiency of about 85%, and an internal optical loss of 9 cm−1.