Using first‐principles band‐structure theory we have systematically calculated the (i) alloy bowing coefficients, (ii) alloy mixing enthalpies, and (iii) interfacial valence‐ and conduction‐band offsets for three mixed‐anion (CuInX2, X=S, Se, Te) and three mixed‐cation (CuMSe2, M=Al, Ga, In) chalcopyrite systems. The random chalcopyrite alloys are represented by special quasirandom structures (SQS). The calculated bowing coefficients are in good agreement with the most recent experimental data for stoichiometric alloys. Results for the mixing enthalpies and the band offsets are provided as predictions to be tested experimentally. Comparing our calculated bowing and band offsets for the mixed‐anion chalcopyrite alloys with those of the corresponding Zn chalcogenide alloys (ZnX, X=S, Se, Te), we find that the larger p−d coupling in chalcopyrite alloys reduces their band offsets and optical bowing. Bowing parameters for ordered, Zn‐based II‐VI alloys in the CuAu, CuPt, and chalcopyrite structures are present...

Band offsets and optical bowings of chalcopyrites and Zn‐based II‐VI alloys

Die vorliegende Erfindung betrifft ein Verfahren zur Bestimmung der Phasen- und/oder Amplitudeninformation einer elektromagnetischen Welle und eine entsprechende Vorrichtung. Um eine raumliche Tiefenauflosung der mit einem solchen Verfahren bei einer Vorrichtung gewonnenen Bildinformation zu erhalten, wird erfindungsgemas ein Verfahren vorgeschlagen, bei dem eine elektromagnetische Welle auf die Oberflache eines mindestens ein Pixel aufweisenden photonischen Mischelementes eingestrahlt wird, wobei das Pixel mindestens zwei lichtempfindliche Modulationsphotogates Gam und Gbm und zugeordnete Akkumulationsgates Ga und Gb aufweist; bei dem an die Modulationsphotogates Gam und Gbm Modulationsphotogatespannungen Uam(t) und Ubm(t) angelegt werden, die als Uam(t) = Uo + Um(t) und Ubm(t) = Um(t) ausgestaltet sind; bei dem an die Akkumulationsgates Ga und Gb eine Gleichspannung angelegt wird, deren Betrag mindestens so gros wie der Betrag der Summe aus Uo und der Amplitude der Modulationsspannung Um(t) ist; bei dem die in der Raumladungszone der Modulationsphotogates Gam und Gbm von der einfallenden elektromagnetischen Welle erzeugten Ladungstrager in Abhangigkeit von der Polaritat der Modulationsphotogatespannungen Uam(t) und Ubm(t) dem Potentialgefalle eines Driftfeldes ausgesetzt werden und zum entsprechenden Akkumulationsgate Ga oder Gb driften; und bei dem die jeweils zu den Akkumulationsgates Ga und Gb gedrifteten Ladungen qa und qb abgeleitet werden. Das entsprechende photonische Mischelement hat mindestens ein Pixel, welches mindestens zwei lichtempfindliche Modulationsphotogates (Gam, Gbm) und den Modulationsphotogates zugeordnete, gegenuber der einfallenden elektromagnetischen Welle abgeschottete Akkumulationsgates (Ga, Gb) aufweist. Mehrere photonische Mischelemente konnen zu einem Array zusammengeschaltet werden.

Verfahren und vorrichtung zur bestimmung der phasen- und/oder amplitudeninformation einer elektromagnetischen welle

Wide band gap semiconductors are essential for today's electronic devices and energy applications because of their high optical transparency, controllable carrier concentration, and tunable electrical conductivity. The most intensively investigated wide band gap semiconductors are transparent conductive oxides (TCOs), such as tin-doped indium oxide (ITO) and amorphous In-Ga-Zn-O (IGZO), used in displays and solar cells, carbides (e.g., SiC) and nitrides (e.g., GaN) used in power electronics, and emerging halides (e.g., γ-CuI) and 2D electronic materials (e.g., graphene) used in various optoelectronic devices. Compared to these prominent materials families, chalcogen-based (Ch = S, Se, Te) wide band gap semiconductors are less heavily investigated but stand out because of their propensity for p-type doping, high mobilities, high valence band positions (i.e., low ionization potentials), and broad applications in electronic devices such as CdTe solar cells. This manuscript provides a review of wide band gap chalcogenide semiconductors. First, we outline general materials design parameters of high performing transparent semiconductors, as well as the theoretical and experimental underpinnings of the corresponding research methods. We proceed to summarize progress in wide band gap (EG > 2 eV) chalcogenide materials-namely, II-VI MCh binaries, CuMCh2 chalcopyrites, Cu3MCh4 sulvanites, mixed-anion layered CuMCh(O,F), and 2D materials-and discuss computational predictions of potential new candidates in this family, highlighting their optical and electrical properties. We finally review applications-for example, photovoltaic and photoelectrochemical solar cells, transistors, and light emitting diodes-that employ wide band gap chalcogenides as either an active or passive layer. By examining, categorizing, and discussing prospective directions in wide band gap chalcogenides, this Review aims to inspire continued research on this emerging class of transparent semiconductors and thereby enable future innovations for optoelectronic devices.

https://escholarship.org/content/qt1xf1k15d/qt1xf1k15d.pdf?t=qof0vs

Wide Band Gap Chalcogenide Semiconductors.

The application of partially coherent laser light to measure intraocular optical distances is discussed In a first step the optical thickness of the retina at the macula and the optical length of the eye has been measured and a precision of ± 0·03 mm has been obtained The results of a comparison with the acoustically determined eye length and first fundus profile measurements are presented

Measurement of Intraocular Optical Distances Using Partially Coherent Laser Light

Many optical measurement techniques provide fringe patterns as their results. The decodification processes that employ one or several fringe patterns to automatically retrieve the phase are generally designated as phase-evaluation methods. In this work, an overview of these methods will be schematically presented. Their particular performances will be compared, stressing their main advantages and drawbacks. An important group of these methods employs the well-known phase-shifting algorithms as a tool for calculating the phase. In the general form of these algorithms, the principal value of the optical phase is computed by an inverse trigonometric function whose argument is a combination of phase-shifted intensity values, provided by the modulation of one or several fringe patterns. These algorithms will be also studied in the general context of the phase-evaluation methods.

https://iopscience.iop.org/article/10.1088/0957-0233/10/3/005/pdf

Phase-evaluation methods in whole-field optical measurement techniques

We propose a new type phase locked interferometer which uses tunability of the wavelength of a laser diode. The phase lock is achieved by controlling the injection current of the laser diode. A CCD image sensor is used as a photodetector to scan electrically a measuring point along the surface of the object. Since this interferometer uses no mechanical elements such as a piezoelectric transducer and galvanomirror, the measurement accuracy is not limited by the mechanical properties. The characteristics of the feedback control system for the phase lock are examined through measurements of surface profiles of the diamond-turned aluminum disks.

Phase locked laser diode interferometry for surface profile measurement

A new signal processing system for real time displacement measurement in sinusoidal phase modulating interferometry is described. Although sinusoidal phase modulating interferometry is effective in measuring with high accuracy the displacement of an object, conventional signal processing takes a long time. In this method, detection of the object's displacement is easily achieved by sampling the interference signal at those times that satisfy certain conditions and by processing the sampled signals with electric circuits in real time. The delay time of this signal processing system is <45 μs.

Real time displacement measurement in sinusoidal phase modulating interferometry

A real-time displacement measurement system using a sinusoidal phase modulating interferometer is proposed and demonstrated. The system utilizes the frequency components of the interference signal to detect the desired phase or the displacement in real time. The real-time phase detector is constructed with simple electronic circuits. The system also has a feedback loop to eliminate external disturbance. It is easy to measure the relatively large displacement that exceeds a half wavelength of the light because the compensation circuit is incorporated into the system to obtain continuous phase outside the region from 0 to 2π.

Real-time displacement measurement using synchronous detection in a sinusoidal phase modulating interferometer

A new type of phase-locked laser diode interferometer that uses self-mixing interference in the optical system is described. The selfmixing interference (SMI) signal is obtained easily by optical feedback, i.e., feeding back the laser beam from the object to the laser diode (LD). The SMI signal can be detected by a photodiode in the package of the LD. Therefore, a beamsplitter, reference mirror, and external photodetector are not required, and an interference signal is obtained using a simple optical system. Although the mechanism of SMI is completely different from that of conventional interference, it is shown that the response of the SMI signal to phase changes is the same as that of conventional interference. We used the phase-locked technique to fix the phase change and demonstrated measurement of absolute distance and displacement.

Self-mixing type of phase-locked laser diode interferometer

A real-time 2-D surface profile measurement system is described. In this system, a laser diode and a 2-D charge-coupled device image sensor are used as a light source and a photodetector, respectively. The phase is detected from the sinusoidal phase-modulating
interference signal using the high-speed electrical circuit. The time required for phase detection is 20 ms for 50 x 40 measuring points. Because the phases can be obtained for even and odd fields of the image
sensor, the original spatial resolution of the image sensor is not reduced in this system. Repeatability of the measurement is -14 nm, rms.

Takeo Maruyama

Papers

Phase locked laser diode interferometry for surface profile measurement

Real time displacement measurement in sinusoidal phase modulating interferometry

Real-time displacement measurement using synchronous detection in a sinusoidal phase modulating interferometer

Self-mixing type of phase-locked laser diode interferometer

Real-time two-dimensional surface profile measurement in a sinusoidal phase-modulating laser diode interferometer