Growth of InGaAsN/InP structures by chemical beam epitaxy

In III-V semiconductors incorporation of small amounts of nitrogen cause a relatively large bandgap reduction. The problem of InGaAsN is the decrease in luminescence with nitrogen content above 1 - 2%.We have grown a.o. In0.65Ga0.35As0.985N0.015 quantum wells. The as-grown samples show poor photoluminescence at 4K but after a high temperature anneal clear peaks are observed. In comparision to ternary layers of In0.65Ga0.35As, the bandgap has decreased by approximately 70 meV due to 1.4 % of nitrogen. A further increase in the nitrogen content could result in layers with a bandgap of 800 meV at room temperature (l = 1.55 mm)

Measurement of the ambipolar carrier capture time in a gallium arsenide/aluminum gallium arsenide separate confinement heterostructure quantum well

The carrier capture in a separate confinement heterostructure quantum well has been studied both experimentally and theoretically. Our calculations show that the electron and hole capture time vary strongly as a function of the excess energy. At an excess energy of 40 meV, both capture times are equal resulting in an ambipolar capture process which allows a direct comparison between theory and experiment. We carried out subpicosecond luminescence spectroscopy experiments and deduce an ambipolar overall capture time of 20 ps, a number which for the first time is in agreement with theoretical predictions. The quantum mechanical overall capture time of 20 ps gives rise to a classical local capture time of 3 ps which is determined from a diffusion model

Vertical-cavity surface-emitting lasers with periodic gain and aluminium top contact

The authors report low threshold current operation of InGaAs/AlGaAs vertical-cavity surface-emitting lasers. A periodic gain structure allows more strained wells to be used than in conventional multiquantum-well devices, offering advantages for high-power devices. Aluminium ohmic contacts grown by molecular beam epitaxy are used on lasers for the first tim

Separate electron-hole confinement in composite InAsyP 1-y/Ga xIn1-xAs quantum wells

Composite double qunatum wells made from materials with a type-II band line-up have been grown to realize separate confinement in real space for electrons and holes. We have observed a substantial blue shift of the lowest energy transition in such composite double quantum wells. The photocurrent measurements demonstrate a linear Stark shift due to the separate confinement in real space for electrons and holes. The charge separation is up to 45 Å in the strain balanced InAs0.42P0.58/Ga0.67In0.33As samples. The experimental results agree very well with calculations in the framework of Bir-Pikus strain Hamiltonian

A chopped quantum-well polarization-independent interferometric switch at 1.53 μm

We have theoretically designed and realized a phase shifter for a low-loss Mach-Zehnder interferometric switch. The phase shifter is based on 0.85% tensile strained InGaAs-InP chopped quantum-well material. We realized a Mach-Zehnder interferometric switch with polarization-independent switching voltages as low as 3.3±0.05 V at 1525 nm for a switch with a 4-mm-long phase shifting section. The wavelength sensitivity of the switch is 0.036 V/nm for TE and 0.053 V/nm for TM polarization. Calculations of the electro-refraction in the -0.85% strained chopped quantum-well (QW) material based on the 4×4 Luttinger-Kohn Hamiltonian show that the electro-refraction due to the quantum-confined Stark effect (QCSE) for TM polarization is equal to the sum of the mutually comparable QCSE electro-refraction and the Pockels effect for TE polarization in waveguides along the [11¯0] axis. Our first-principle model for calculating the electro refraction is an accurate design tool for predicting device performance in complicated layer structures. The shortest possible phase shifter with