We present models for the optical functions of 11 metals used as mirrors and contacts in optoelectronic and optical devices: noble metals (Ag, Au, Cu), aluminum, beryllium, and transition metals (Cr, Ni, Pd, Pt, Ti, W). We used two simple phenomenological models, the Lorentz-Drude (LD) and the Brendel-Bormann (BB), to interpret both the free-electron and the interband parts of the dielectric response of metals in a wide spectral range from 0.1 to 6 eV. Our results show that the BB model was needed to describe appropriately the interband absorption in noble metals, while for Al, Be, and the transition metals both models exhibit good agreement with the experimental data. A comparison with measurements on surface normal structures confirmed that the reflectance and the phase change on reflection from semiconductor-metal interfaces (including the case of metallic multilayers) can be accurately described by use of the proposed models for the optical functions of metallic films and the matrix method for multilayer calculations.

Optical properties of metallic films for vertical-cavity optoelectronic devices.

The role of extended and point defects, and key impurities such as C, O, and H, on the electrical and optical properties of GaN is reviewed. Recent progress in the development of high reliability contacts, thermal processing, dry and wet etching techniques, implantation doping and isolation, and gate insulator technology is detailed. Finally, the performance of GaN-based electronic and photonic devices such as field effect transistors, UV detectors, laser diodes, and light-emitting diodes is covered, along with the influence of process-induced or grown-in defects and impurities on the device physics.

Gan : processing, defects, and devices

1. Introduction and overview 2. Film stress and substrate curvature 3. Stress in anisotropic and patterned films 4. Delamination and fracture 5. Film buckling, bulging and peeling 6. Dislocation formation in epitaxial systems 7. Dislocation interactions and strain relaxation 8. Equilibrium and stability of surfaces 9. The role of stress in mass transport.

Thin Film Materials: Stress, Defect Formation and Surface Evolution

The ability to control the modes oscillating within a laser resonator is of fundamental importance. In general, the presence of competing modes can be detrimental to beam quality and spectral purity, thus leading to spatial as well as temporal fluctuations in the emitted radiation. We show that by harnessing notions from parity-time (PT) symmetry, stable single–longitudinal mode operation can be readily achieved in a system of coupled microring lasers. The selective breaking of PT symmetry can be used to systematically enhance the maximum attainable output power in the desired mode. This versatile concept is inherently self-adapting and facilitates mode selectivity over a broad bandwidth without the need for other additional intricate components. Our experimental findings provide the possibility to develop synthetic optical devices and structures with enhanced functionality.

http://science.sciencemag.org/content/sci/346/6212/975.full.pdf

Parity-time–symmetric microring lasers

In this review article a comprehensive analysis of the developments in ultraviolet (UV) detector technology is described. At the beginning, the classification of UV detectors and general requirements imposed on these detectors are presented. Further considerations are restricted to modern semiconductor UV detectors, so the basic theory of photoconductive and photovoltaic detectors is presented in a uniform way convenient for various detector materials. Next, the current state of the art of different types of semiconductor UV detectors is presented. Hitherto, the semiconductor UV detectors have been mainly fabricated using Si. Industries such as the aerospace, automotive, petroleum, and others have continuously provided the impetus pushing the development of fringe technologies which are tolerant of increasingly high temperatures and hostile environments. As a result, the main efforts are currently directed to a new generation of UV detectors fabricated from wide band‐gap semiconductors the most promising ...

Semiconductor ultraviolet detectors

We have proposed and demonstrated a novel 1.5-/spl mu/m-GaInAsP microcylinder laser with low refractive index InAlAs(O/sub x/) claddings, which allows the strong optical confinement as in a microdisk. The effective threshold current density was 25% lower than that for the previous 0.98-/spl mu/m-GaInAs device. The selective oxidation of the claddings is expected to further reduce the threshold and extend the feasibility of this type of device in large scale photonic circuits.

http://ieeexplore.ieee.org/iel5/6269/16744/00773673.pdf

A novel GaInAsP microcylinder laser with AlInAs(O/sub x/) claddings

GaAlAs/GaAs MOCVD Growth for Surface Emitting Lasers

Low Threshold Room Temperature Pulsed and -31 °C CW Operations of 1.3 µm GaInAsP/InP Buried Heterostructure Surface Emitting Lasers

The effects of using strained layer superlattice in multiquantum barriers (MQBs) were analyzed with focus on InP-based materials and their application to strained layer multiquantum well lasers (SL-MQW LDs). Tensile strained barriers are shown to largely increase the effective barrier height of MQBs. A new barrier material, AlInP, which is 1–1.5% tensile strained on InP, is shown to have inherent advantages of large conduction band edge discontinuity ΔEc and low aluminum content compared to conventional AlInAs on InP. Those advantages are confirmed for strain-compensated MQB with tensile barrier/compressive well in terms of increasing the effective barrier height. Some disadvantages of the strain-compensated MQB are also pointed out; the increase in density of holes injected into the MQB region under lasing conditions and the high p-doping concentration required. To solve those problems, an improved method of carrier injection through minibands with gradually enhanced energy levels toward the MQW region is presented, which is shown to enable elimination of the carrier transport effect and to result in marked improvement in laser performances.

Kenichi Iga

Papers

A novel GaInAsP microcylinder laser with AlInAs(O/sub x/) claddings

GaAlAs/GaAs MOCVD Growth for Surface Emitting Lasers

Low Threshold Room Temperature Pulsed and -31 °C CW Operations of 1.3 µm GaInAsP/InP Buried Heterostructure Surface Emitting Lasers

Strained Layer Multiquantum Barriers with Improved Carrier Injection and Confinement

Temperature Characteristics of Lambda=1.3 mum GaInNAs/GaAs Quantum Well Lasers Grown by Chemical Beam Epitaxy