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The first superlattice avalanche photodiode (APD) is reported. The high field region of this p-i-n structure consists of 50 alternating Al0.45Ga0.55As (550 Å) and GaAs (450 Å) layers. A large ionization rate ratio has been measured in the field range (2.1–2.7)×105 V/cm, with α/β≃10 at a gain of 10 giving a McIntyre noise factor Fn = 3. The ionization rate ratio enhancement with respect to bulk GaAs and AlGaAs is attributed to the large difference in the band edge discontinuities for electrons and holes at the heterojunction interfaces. The superlattice APD is a new device concept which can be used to develop low noise APD’s in a variety of III-V materials including long wavelength 1.3–1.6-μm semiconductors.

Extremely low threshold GRIN-SCH lasers with single and double active layers were prepared by molecular beam epitaxy as a result of an increased optical confinement, a significant reduction in the internal loss αi, and the increased gain constant β. Averaged Jth 250 A/cm2 and 160 A/cm2 for broad-area Fabry–Perot diodes of cavity lengths 380 and 1125 μm, respectively, and averaged external differential quantum efficiency ηD of 65–80 % were obtained.

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