We report bulk GaInNAs p − i − n photodiodes lattice-matched to GaAs substrates, grown by solid source molecular beam epitaxy with photoresponses out to ϳ1.3 m. The as-grown samples were characterized optically, structurally, and electrically. A low background doping concentration in the range of 10 14 -10 15 cm −3 was obtained in the samples. One of the samples with a 0.5 m thick GaInNAs absorbing layer gave a responsivity of 0.11 A/W for a band edge of 1.28 m at reverse bias of 2 V.

The growth temperature of spacer layers (SPLs) is investigated as a means to obtain identical layers for multilayer quantum dot (QD) structures. A 5-layer 1.3-μm InAs∕GaAs QD structure with 50-nm GaAs SPLs served as a model system. It is found that the growth temperature of the GaAs SPLs has pronounced effects on both the structural and optical properties of the InAs QDs. For GaAs SPLs grown at a low temperature of 510°C, dislocations are observed in the second and subsequent layers, a result of significant surface roughness in the underlying spacer layer. However by increasing the growth temperature to 580°C for the final 35nm of the 50-nm GaAs SPLs, a much smoother surface is achieved, allowing the fabrication of essentially identical, defect free QD layers. The suppression of defect formation enhances both the room-temperature photoluminescence efficiency and the performance of 1.3-μm multilayer InAs∕GaAs QD lasers. An extremely low continue-wave room-temperature threshold current density of 39A∕cm2 is achieved for an as-cleaved 5-layer device with emission at 1.306μm and ground state operation up to 100°C.

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Role of Sb in the growth and optical properties of 1.55 μ m Ga In N ( Sb ) As ∕ Ga N As quantum-well structures by molecular-beam epitaxy

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The anomalous behavior of impact ionization in dilute-nitride GaInNAs photodiodes with a range of nitrogen content below 4% is investigated. The ratio of hole- and electron-initiated ionization coefficients, k = β/α, is enhanced by a factor up to ∼4 with increasing nitrogen content. The absolute ionization coefficients are suppressed by up to two orders of magnitude at low electric fields in samples with 3% N. The narrow band gap, suppressed impact ionization, and increased breakdown voltage characteristics of GaInNAs make it a suitable material for use as part of a composite collector in GaAs-based heterojunction bipolar transistors.