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

The long wavelength GaInAsP/InP surface emitting (SE) laser is becoming important for use in optical fiber networks. We reported a low threshold GaInAsP/InP SE laser grown by chemical beam epitaxy (CBE) with some device characteristics. However, its temperature dependence on threshold and efficiency are inferior to those of short wavelength SE lasers. The auger process and intervalence band absorption were discussed as the primary causes of the worse temperature characteristic. In addition to these, the potential spike at the active layer and p-cladding hetero-interface may require an additional voltage bias to inject holes. Takemoto et al. proposed a band discontinuity reduction (BDR) layer to reduce the spike height. Kazarinov et al. Pointed out that this spike reduces a potential barrier for electron confinement in the active layer and increases an electron overflow to the p-cladding layer. A preliminary calculation shows the carrier overflow may degrade the performance of long wavelength SE lasers. In this study, we investigate the current-voltage characteristic of the hetero-interface and introduce a BDR layer which has an intermediate composition between the active layer and the p-cladding layer in order to improve the temperature characteristic of long wavelength SE lasers. >

Band discontinuity reduction of i-GaInAsP/p-InP for improving 1.55 /spl mu/m GaInAsP/InP surface emitting laser performances

The GaInNAs/GaAs system has been attracting much interest for 1.3 /spl mu/m monolithic vertical cavity surface emitting lasers (VCSELs). So far, room temperature operations of 1.3 /spl mu/m GaInNAs/GaAs edge emitting lasers grown by either gas source MBE or MOCVD have been demonstrated. However, the degradation of crystal qualities with increasing the nitrogen composition is a remaining problem. The origin for the deterioration is still unclear. It is essential to find the origin and to improve the quality of GaInNAs for realizing high performance long wavelength GaInNAs lasers. In this work, we present the composition dependence of emission characteristics of highly strained GaInNAs quantum well lasers, including the carrier lifetime, the spontaneous emission efficiency and the threshold current density. A prospect of long wavelength GaInNAs VCSELs for high speed LANs is also discussed.

Composition dependence of carrier lifetime and spontaneous emission of highly strained GaInNAs/GaAs QW lasers

Liquid-Phase Epitaxy (LPE) has many advantages and is capable of producing reliable semiconductor devices. This chapter provides a detailed description of the equipment necessary for LPE and the epitaxial techniques required for double heterostructures. As discussed in Chap. 4, the principle behind LPE is very simple: epitaxial layers can be thermodynamically grown on a substrate with the same orientation when the substrate meets the oversaturated solution. Since semiconductor-laser research began, LPE has been a popular growth technique and it still plays an important role in producing semiconductor lasers, light emitting diodes and photodetectors.

Liquid Phase Epitaxy and Growth Technology

Temperature characteristics of short-cavity AlGaAs/GaAs surface emitting lasers

We have estimated the characteristic temperature T0 of GaN-based vertical-cavity surface-emitting lasers. The density matrix theory including intraband relaxation broadening has been taken into account. The estimated T0 is about 300 K, which suggests a good temperature characteristic in GaN-based lasers.

Kenichi Iga

Papers

Band discontinuity reduction of i-GaInAsP/p-InP for improving 1.55 /spl mu/m GaInAsP/InP surface emitting laser performances

Composition dependence of carrier lifetime and spontaneous emission of highly strained GaInNAs/GaAs QW lasers

Liquid Phase Epitaxy and Growth Technology

Temperature characteristics of short-cavity AlGaAs/GaAs surface emitting lasers

Characteristic Temperature Estimation for GaN-Based Lasers