The unusual N-induced band formation and band structure of Ga(N, As) and (Ga, In)(N, As) alloys are also reflected in the electronic structure of quantum wells (QWS) and device structures containing these non-amalgamation-type alloys. This review is divided into three parts. The first part deals with band structure aspects of bulk Ga(N, As) and motivates the possibility of a k•p-like parameterization of the band structure in terms of the level repulsion model between the conduction band edge of the host and a localized N-level. The second part presents experimental studies of interband transitions in Ga(N, As)/GaAs and (Ga, In)(N, As)/GaAs QW structures addressing band offsets, electron effective mass changes and an intrinsic mechanism contributing to the blueshift of the (Ga, In)(N, As) band gap on annealing. The observed interband transitions can be well described using a ten-band k•p model based on the level repulsion scheme. The third part deals with (Ga, In)(N, As)-based laser devices. The electronic structure of the active region of vertical-cavity surface-emitting laser and edge-emitter laser structures is studied by modulation spectroscopy. The gain of such structures is measured by optical methods and analysed in terms of a model combining the ten-band k•p description of the band structure and generalized Bloch equations.

The absorption and gain for an InGaNAs/GaAs quantum-well structure is calculated and compared to that of a more conventional InGaAs/InGaPAs structure, both lasing in the 1.3 μm range. Despite significant differences in the band structures, the gain value is comparable for high carrier densities in both structures and the transition energy at the gain maximum shows a similar blueshift with increasing carrier density. For low and intermediate carrier densities, the calculated gain in the InGaPAs system is significantly lower and the bandwidth smaller than in the InGaNAs system.

We describe the experimental cw power scaling of optically pumped semiconductor disk lasers OPS-DLs and give a detailed insight into the physical mechanism of this type of high-power surface-emitting semiconductor laser with external cavity. Minimizing the thermal resistance between active region and heat sink enables improved efficiency and gives access to high power and excellent beam quality of OPS-DL at 1000 nm. Results from initial numerical modeling are in good agreement with the experimental data, and show that thermal management is a critical parameter for the temperature-driven power shutoff in such devices. The computations are based on the macroscopic thermal transport, spatially resolved in both the radial and longitudinal directions, and coupled to the carrier density rate equations. A quantitative microscopic approach is used for the quantum-well gain and absorption dependence on wavelength, carrier density, and lattice temperature. The dependence of the computed output power on the substrate thickness and detuning are discussed.

A detailed analysis of the optical and transport properties of semiconductor superlattices in the high-field regime is presented. Electronic Bloch oscillations and the resulting terahertz emission signals are computed including phonon damping in the presence of the electric field. The modifications of the phonon-induced terahertz signal decay are analyzed including the movement of the carriers in the field~intracollisional field effect!. For elevated fields it is shown that the interplay between electric field and electron-phonon interaction leads to resonance structures in the terahertz damping rate. @S0163-1829~97!05620-8#

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