The semiconductor ZnO has gained substantial interest in the research community in part because of its large exciton binding energy (60meV) which could lead to lasing action based on exciton recombination even above room temperature. Even though research focusing on ZnO goes back many decades, the renewed interest is fueled by availability of high-quality substrates and reports of p-type conduction and ferromagnetic behavior when doped with transitions metals, both of which remain controversial. It is this renewed interest in ZnO which forms the basis of this review. As mentioned already, ZnO is not new to the semiconductor field, with studies of its lattice parameter dating back to 1935 by Bunn [Proc. Phys. Soc. London 47, 836 (1935)], studies of its vibrational properties with Raman scattering in 1966 by Damen et al. [Phys. Rev. 142, 570 (1966)], detailed optical studies in 1954 by Mollwo [Z. Angew. Phys. 6, 257 (1954)], and its growth by chemical-vapor transport in 1970 by Galli and Coker [Appl. Phys. ...

/pdf/a-comprehensive-review-of-zno-materials-and-devices-21a3zjadem.pdf

A comprehensive review of zno materials and devices

In this paper we report measurements of the effects of large static uniaxial stress along [001], [111], and [110] on the frequency of the $\stackrel{\ensuremath{\rightarrow}}{\mathrm{k}}\ensuremath{\approx}0$ optical phonons in Ge, GaAs, GaSb, InAs, and ZnSe using first-order Raman scattering. In the absence of stress, the first-order Stokes-Raman spectrum of diamond-type materials exhibits a single peak which corresponds to the $\stackrel{\ensuremath{\rightarrow}}{\mathrm{k}}\ensuremath{\approx}0$ triply degenerate optical phonons (${F}_{2g}$ or ${\ensuremath{\Gamma}}_{{25}^{\ensuremath{'}}}$) while the zinc-blende materials exhibit two peaks, corresponding to the $\stackrel{\ensuremath{\rightarrow}}{\mathrm{k}}\ensuremath{\approx}0$ LO and TO phonons. The application of the uniaxial stress causes polarization-dependent splittings and/or shifts which are linear in the stress. From these observed splittings and shifts we have obtained experimental values for the phenomenological coefficients ($p, q, \mathcal{r}$) which describe the changes in the "spring constant" of these optical phonons with strain. Comparison of the experimental values is made with several theoretical considerations based on bond-stretching and bond-bending interactions between atoms. The shift due to the hydrostatic component of the strain yields a value for the mode-Gr\"uneisen parameter, which is compared with the results of hydrostatic-pressure measurements. For the zinc-blende-type materials, the doubly degenerate TO-phonon line exhibits both a splitting and shift with stress, while only a shift is observed for the singlet LO-phonon line. In the case of the III-V compounds, one of the split TO lines has a stress dependence equal to that of the LO-phonon line, while this is not the case for the group II-VI material (ZnSe) we have investigated. This latter result is interpreted in terms of the stress dependence of the effective charge.

Stress-Induced Shifts of First-Order Raman Frequencies of Diamond- and Zinc-Blende-Type Semiconductors

Gallium nitride was studied by Raman scattering and x-ray-absorption spectroscopy up to 60 GPa. A high-pressure structural phase transition was observed in gallium nitride at 47 GPa by means of Raman scattering and x-ray-absorption spectroscopy. We also report the direct determination of the bulk modulus ${\mathit{B}}_{0}$ of this compound (245 GPa). Gr\"uneisen parameters of the four observed phonon modes were established. The transition pressure is compared with existing calculations.

Raman scattering and x-ray-absorption spectroscopy in gallium nitride under high pressure.

The high-pressure behavior of optical phonons in wurtzite zinc oxide $(w\ensuremath{-}\mathrm{ZnO})$ is studied using room-temperature Raman spectroscopy and ab initio calculations based on a plane-wave pseudopotential method within the density-functional theory. The pressure dependence of the zone-center phonons ${(E}_{2},{A}_{1},$ and ${E}_{1})$ was measured for the wurtzite structure up to the $\mathrm{hexagonal}\ensuremath{\rightarrow}\mathrm{cubic}$ transition near 9 GPa. Above this pressure no active mode was observed. The only negative Gr\"uneisen parameter is that of the ${E}_{2}^{\mathrm{low}}$ mode. ${E}_{1}(\mathrm{LO})$ and (TO) frequencies increase with increasing pressure. The corresponding perpendicular tensor component of the Born's transverse dynamic charge ${e}_{T}^{*}$ is experimentally found to increase under compression like ${e}_{T}^{*}(P)=2.02+6.4\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}P,$ whereas calculations give ${e}_{T}^{*}(P)=2.09--2.5\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}P$ (in units of the elementary charge e, P in GPa). In both cases, the pressure variation is small, indicating a weak dependence of the bond ionicity with pressure. The pressure dependence of the optical mode energies is also compared with the prediction of a model that treats the wurtzite-to-rocksalt transition as an homogeneous shear strain. There is no evidence of an anomaly in the ${E}_{2}$ and ${A}_{1}$ mode behaviors before the phase transition.

/pdf/high-pressure-raman-spectroscopy-study-of-wurtzite-zno-1ebj80tscu.pdf

High-pressure Raman spectroscopy study of wurtzite ZnO

Effects of annealing on properties of ZnO thin films prepared by electrochemical deposition in chloride medium

Pressure shifts of long-wavelength LO and TO phonons of a number of diamond-, zinc-blende-, and wurtzite-type crystals as functions of hydrostatic pressure have been investigated by Raman-scattering measurements. The measured Gr\"uneisen parameters appear to correlate with ionicity. The ${E}_{2}$ modes of CdS and ZnO have also been studied.

Pressure-Induced Phonon Frequency Shifts Measured by Raman Scattering

The infrared transmittance and reflectance of pure crystals of ZnS and ZnSe have been reported several years ago(1–4) The optically active phonon processes in ZnSxSe1-x crystals have been investigated here by infrared reflection, transmission and Raman spectroscopy for nine values of x between 0 and 1. We believe this is the first mixed crystal system to receive such a thorough treatment. Previous studies(5) on mixed zincblende- and wurtzite-type crystals were confined chiefly to reflection measurements and were thus limited to the elucidation of the transverse optic (TO) phonons at k~0. Direct evidence on k~0 longitudinal optic (LO) phonons are obtained from present Raman measurements. It became evident that the behavior of the present system is by far the most interesting case inasmuch as it neither behaves like ionic mixed crystals nor like covalent mixed crystals. In mixed systems composed of primarily ionic crystals(6) e.g. NixCo1-xO, KCxBr1-x, NaxRb1-xI, CaxSr1-xF2 etc., due to the presence of long range Coulomb interactions only a single reststrahlen band occurs and the long wavelength LO and TO modes shift continuously and linearly with concentration.

Optical phonons in ZnSxSe1-x mixed crystals

Pressure dependence of Raman spectra of solids. Phase transition in TlI

Lattice dynamics of cubic zinc sulfide

Optical Phonons in ZnS x Se 1-x Mixed Crystals

Handle everyday research tasks with reliable, citation-backed results

Your personal Research Agent to handle research tasks with citation-backed results

Popular Tasks used by Researchers

How can I help with your research?

Meet SciSpace

Get more enhanced response by uploading the PDFs you want me to reference.

No relevant PDFs in your library

SciSpace is the AI research assistant for academics. Run systematic literature reviews on 280M+ papers, and write papers with cited sources. Trusted by 1M+ students, PhDs & researchers.

SciSpace | AI for Research

Analyze PDFs

Code & Manuscripts

Funding & Grants

Literature & Patents

Medical & Clinical Data

Systematic Review

Visualize & Present

Web & Data

Build a Google Scholar-like website for your research.

Build a website

Create charts and images for your research

Create a Chart

Write a paper for submission to a journal

Draft a manuscript

Patent Search

Design eye-catching scientific posters in minutes.

Scientific Poster Generation

Systematic Literature Review

One task is running at the moment. Your messages will be shown right after.

Drag and drop or click here to browse

Loved by <highlight>1 million+</highlight> researchers

Extract a list of specific topics and their sources from unstructured text

Topics

Compare and analyze relevant papers that matches with your search

Papers

Get insights from PDFs and bookmarked papers from your library

My library

Recent searches

Try searching for:

Catch AI-generated content in scholarly and non-scholarly content

{ai} Detector

Ai Writer

Get PDF Summaries, highlighted text explanations 

Chat with PDF

Effortlessly create in-text citations and bibliographies in APA and 2,500 other formats

Citation generator

Get explanations, summaries, and answers on academic papers

Ease up your research workflow with {scispace}'s cohort of exciting AI tools

Elevate your academic writing skills and convey your ideas the way you want

Paraphraser

Explore our range of reading and writing tools

Your file is being prepared and should be ready in a few minutes. If it's a large file, it might take a bit longer. You can close this window, and we'll email you the file when it's done.

You have reached a maximum limit of <strong>{limit}</strong> columns in the table. Remove at least <strong>1</strong> column to add or create another one.

O. Brafman

Author Tools

Chat about Author