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High (42.5%) indium content GaInNAs/GaAs quantum wells with room temperature emission wavelength from 1.3 μm to 1.5 μm range were successfully grown by Radio Frequency Plasma Nitrogen source assisted Molecular Beam Epitaxy. The growth parameters of plasma power and N2 flow rate were optimized systematically to improve the material quality. Photoluminescence and transmission electron microscopy measurements showed that the optical and crystal quality of the 1.54 μm GaInNAs/GaAs QWs was kept as comparable as that in 1.31 μm.

The roughness and the crystallographic orientation selectivity of etched antimonide-based infrared materials are examined and are used to optimize the chemical mesa etching process of the InAs/GaSb superlattice photodiode with the goal of reducing the dark current. The etchant used is based on phosphoric acid (H3PO4), citric acid (C6H8O7) and hydrogen peroxide (H2O2). The roughness of the mesa sidewalls and etching rates are compared and used to find an optimized etchant, with which we obtain optimized mid-wavelength infrared photodiodes possessing an R0A value of 466 ωcm2 and a detectivity of 1.43 × 1011 cmHz1/2 W−1. Crystallographic orientation selectivity is seen in InAs etching, and also is seen in the InAs/GaSb superlattice wet chemical etching process.

The GaSb-based laser shows its superiority in the 3–4 μm wavelength range. However, for a quantum well (QW) laser structure of InGaAsSb/AlGaInAsSb multiple-quantum well (MQW) grown on GaSb, uniform content and high compressive strain in InGaAsSb/AlGaInAsSb are not easy to control. In this paper, the influences of the growth temperature and compressive strain on the photoluminescence (PL) property of a 3.0-μm InGaAsSb/AlGaInAsSb MQW sample are analyzed to optimize the growth parameters. Comparisons among the PL spectra of the samples indicate that the In0.485GaAs0.184Sb/Al0.3Ga0.45In0.25As0.22Sb0.78 MQW with 1.72% compressive strain grown at 460 °C posseses the optimum optical property. Moreover, the wavelength range of the MQW structure is extended to 3.83 μm by optimizing the parameters.

Molecular beam epitaxy growth of a bilayer stacked InAs/GaAs quantum dot structure on a pure GaAs matrix has been systemically investigated. The influence of growth temperature and the InAs deposition of both layers on the optical properties and morphologies of the bilayer quantum dot (BQD) structures is discussed. By optimizing the growth parameters, InAs BQD emission at 1.436 μm at room temperature with a narrower FWHM of 27 meV was demonstrated. The density of QDs in the second layer is around 9 × 109 to 1.4 × 1010 cm−2. The BQD structure provides a useful way to extend the emission wavelength of GaAs-based material for quantum functional devices.

InAs/GaSb superlattice (SL) midwave infrared photovoltaic detectors are grown by molecular beam epitaxy on GaSb(001) residual p-type substrates. A thick GaSb layer is grown under the optimized growth condition as a buffer layer. The detectors containing a 320-period 8ML/8ML InAs/GaSb SL active layer are fabricated with a series pixel area using anode sulfide passivation. Corresponding to 50% cutoff wavelengths of 5.0 mu m at 77 K, the peak directivity of the detectors is 1.6 x 10(10) cm.Hz(1/2) W-1 at 77 K.

We obtain low-density charged InAs quantum dots with an emission wavelength below 1 mu m using a low InAs growth rate. The quantum dots have a bimodal size distribution with an emission wavelength of around 1340 nm and 1000 nm, respectively. We observe the photoluminescence of the singly charged exciton in the modulation doped quantum dots in 77 K.

A bilayer stacked InAs/GaAs quantum dot structure grown by molecular beam epitaxy on an In0.05Ga0.95As metamorphic buffer is investigated. By introducing a InGaAs Sb cover layer on the upper InAs quantum dots (QDs) layers, the emission wavelength of the QDs is extended successfully to 1.533 mu m at room temperature, and the density of the QDs is in the range of 4 x 10(9) -8 x 10(9) cm(-2). Strong photoluminescence (PL) intensity with a full width at half maximum of 28.6 meV of the PL spectrum shows good optical quality of the bilayer QDs. The growth of bilayer QDs on metamorphic buffers offers a useful way to extend the wavelengths of GaAs-based materials for potential applications in optoelectronic and quantum functional devices.

The nanocrystalline(nc) Ge embedded in SiO2 matrix was attempted to synthesize from thermal oxidation of PECVD deposited ａ-GexSi1-x∶H films.The microstructures of the samples were detected by Fourier transform infrared spectroscopy,Raman spectroscopy and XRD.The results reveal that Ge nanocrystals form during oxidation and their numbers and sizes are varied with different Ge content in the as deposited ａ-GexSi1-x∶H alloy and also changed upon different-oxidation conditions.These characteristics may be due to the selective oxidation of Si in ａ-GexSi1-x∶H alloy and the reduction of hydrogen existing in the samples in view of chemical thermodynamic equilibrium. Some nc-Si samples display visible photoluminescence(PL) at room temperature.Based on Brus, exiton three-dimensional quantum confinement model,the nc-Ge size was evaluated from the PL peak positions and show a good agreement with the result of XRD.All the above analyses suggest that nc-Ge buried in SiO2 matrix can be obtained by the present method and its visible photoluminescence is related to the effect of quantum size on nc-Ge.The observation of nc-Ge with TEM is required to further confirm these facts.