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 demonstrated a single-transverse-mode and stable-polarization GaInAs/GaAs vertical-cavity surface-emitting laser (VCSEL) array grown on a GaAs(311)B substrate. A fabricated 3×3 VCSEL array consists of devices with an oxide aperture of 3.4 µm×3.4 µm and exhibited single-transverse mode operation with an injection current up to three times the threshold. The Side-mode suppression ratio (SMSR) is larger than 30 dB. The array also exhibits stable-polarization operation with an orthogonal polarization suppression ratio (OPSR) of over 25 dB. The threshold current was 0.61±0.05 mA and the threshold voltage was 1.79±0.03 V. The obtained uniform single-mode array characteristics are due to the high uniformity and controllability of the improved oxidation process.

https://iopscience.iop.org/article/10.1143/JJAP.39.L588/pdf

Vertical-Cavity Surface-Emitting Laser Array on GaAs(311)B Substrate Exhibiting Single-Transverse Mode and Stable-Polarization Operation

An Analysis on Single Wavelength Oscillation of Semiconductor Laser at High Speed Pulse Modulation

An ultra-high density optical memory using near field optics has been attracting much interest for future data storage. Betzig and coworkers (1992) demonstrated optical recording by an optical scanning microscope (NSOM) and suggested the possibility of tera byte data storage. One of the authors (K. Goto) proposed (1998) a tera byte optical memory system using a VCSEL array. One of the key issues in the proposed optical disk system is to realize an optical head consisting of a 2-dimensional VCSEL array. In near-field optics memory, there still remains the difficulty in getting a high output power efficiently from a sub-wavelength sized aperture. It is especially important to realize a high efficiency VCSEL for optical heads by reducing the total power consumption in arrays. We proposed a metal aperture VCSEL for producing near field light with high efficiency. In the study, we carried out a near field analysis of a micro-aperture VCSEL and present some basic process technologies for realizing the proposed device.

https://ieeexplore.ieee.org/iel5/6572/17626/00817748.pdf

Micro-aperture surface emitting laser for near field optical data storage

We measured the chlorine plasma characteristics in reactive ion beam etching (RIBE) and chemically assisted ion beam etching (CAIBE) process. In the CAIBE process, the energy peak of Cl+ ionized by Ar+ appears in the energy range of 50–70 eV and this Cl+ energy peak increases with an increase of Ar+ energy. We observed that the excited state Cl2 density in CAIBE is lower than that in RIBE as measured by appearance mass spectrometry (AMS).

Plasma Characterization in Chlorine-Based Reactive Ion Beam Etching and Chemically Assisted Ion Beam Etching.

The semiconductor laser has been taking an important role in optoelectronics and IT backbones and will be keeping its position for the coming at least 10 years. There would still be a lot of chances to meet really novel subjects in research and development, e.g. the coverage of full spectral ranges, temperature insensitive operation, ultra-high power capability, frequency control, large scale integration, and so on. In this paper, we like to discuss of the semiconductor laser for tomorrow based upon the experience of founding research of vertical cavity surface emitting laser.

Kenichi Iga

Papers

Vertical-Cavity Surface-Emitting Laser Array on GaAs(311)B Substrate Exhibiting Single-Transverse Mode and Stable-Polarization Operation

An Analysis on Single Wavelength Oscillation of Semiconductor Laser at High Speed Pulse Modulation

Micro-aperture surface emitting laser for near field optical data storage

Plasma Characterization in Chlorine-Based Reactive Ion Beam Etching and Chemically Assisted Ion Beam Etching.

Semiconductor laser in the 21st century