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Register a new userStudy the possibility of using thin films of ZnO as an effective medium for random laser
دراسة إمكانية استخدام أغشية رقيقة من الـ ZnO كوسط فعال لليزر عشوائي
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Damascus University مقالة
Publication date
2020
fields
Physics
and research's language is
العربية
Created by
Saeed Maroof
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حُضِّرت وبنجاح أغشية رقيقة من أكسيد الزنك ZnO بسماكات مختلفة على ركائز زجاجية باستخدام طريقة السول – جل وذلك باستخدام خلات الزنك المائية كمصدر رئيسي لشوارد الزنك Zn+2. شُخصت مورفولوجيا السطح بواسطة مجهر القوة الذرية (AFM) ووصّفت الأغشية المحضرة بنيوياً بواسطة طيف انعراج الأشعة السينية (XRD) أما التحليل العنصري فقد تم بواسطة مطيافية تشتت الطاقة للأشعة السينية (EDX). كما دُرِست الخواص الضوئية للأغشية المحضرة بواسطة المطيافية الضوئية تحت الأحمر- المرئي - فوق البنفسجية UV – VIS – IR والتألق الضوئي (PL). أظهرت صور الـ AFM أن الأغشية المحضرة ناعمة ومتجانسة وخصوصاً في أجل السماكات العالية وأن الحبيبات الناتجة على السطح تأخذ شكل قضبان متقطعة متوسط قطرها يساوي 240nm. لوحظ عن طريق طيف الـ XRD أن التوجه البلوري السائد للغشاء المحضر هو (112) وأن ابعاد بلوراته يساوي 19nm، في حين أظهرت طيف الـ EDX أن التركيب العنصري لتلك الأغشية هو من أكسيد الزنك. من خلال المطيافية UV – VIS – IR تبين أن تلك الأغشية تملك نفاذية عالية في المجال المرئي كما حُسِبت قيمة الفجوة الطاقية المباشرة للأغشية المحضرة بدلالة السماكة والتي تراوحت بين (3.273 – 3.256 eV). لوحِظ من خلال مطيافية التألق الضوئي وجود قمة إصدار عند الطول الموجي 616nm هذا ما يرشحها لأن تكون وسط فعال لليزر العشوائي.
Thin films of ZnO were successfully prepared on glass substrates with different thicknesses by sol-gel method by using zinc acetate dehydrate as precursor. The surface of thin films morphology from were studied by AFM micrographs, the structural properties of the obtained ZnO thin film are studied using X-ray diffraction spectra and their elemental analysis by X-ray energy dispersion spectroscopy (EDX). Moreover, optical properties and emission of ZnO nano thin film were evaluate during ultraviolet-visible-infrared and photoluminescence spectra. The AFM investigations have revealed that the morphology of the films is smooth and homogeneous specially for the high thickness and the grains produced on the surface take the form of nano rods with an average diameter of 240nm. Structural analysis by X-ray diffraction showed that the deposited films have a preferred orientation along the direction (112) and are relatively uniform with average crystal size 19nm, while the EDX spectrum showed that the elemental composition of these films is zinc oxide. The spectrophotometer Ultraviolet -Visible confirms that it is possible to get good transparent ZnO films with a transmission of 77 to 92% in the infrared. The values of optical gaps Eg vary between 3.273 - 3.256 eV. The peak of photoluminescence exhibited a visible emission peak at 616nm that refers to possibility of using thin films as an effective medium of random laser.
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In the present paper, we discuss the influence of point defects on electrical and
optical characteristics of ZnO thin films grown by the atomic layer deposition (ALD)
method on glass and silicon substrates at low temperature (100°C). Room temperatu
re
photoluminescence (RT PL) spectra, secondary ion mass spectroscopy (SIMS), and Hall
Effect measurements were made for as-grown ZnO layers. The annealing process was
performed in air as well as in N2 atmosphere at 400°C for half an hour. The long annealing
resulted in a larger reduction in electron concentration. Simultaneously, an evident
increase in carrier's mobility was observed, which may suggest that annealing resulted in a
decreased number of native defects in the ZnO layers. Also, it was observed that hydrogen
atoms in ZnO samples did not dominate their electrical properties with the increase of
electrons concentration.
A study of surface chemical composition has been performed by using Auger Electron Spectroscopy (AES) for ZnO layers grown by Atomic Layer Deposition (ALD) procedure.Elements on surface of materials were identified,and, an atomic concentration of ele
ments on surface was determinate. Onlysmall amount of carbon or carbon compounds detected, easily removed by argon ion sputtering. Also, long argon ion sputtering partly depleted surface of oxygen.
The work could be considered as a continuous study of (XRL) X – ray luminescence - spectra of pure, and mixed Zno different AL ions, In these films and other crystals powders prepared by new developed te chnology.
We studied the pure and ZnO thin
films. mixed with an AL - ions in the fielol (200-700)nm ,at different weig hrs (5,10,15,20)wt% prepared by thermal evaporation. This way is cheep and a simple technology.
Our study showed different spectra peaks at the wavelengths(335,410,521)nm anol (t=20ns)produced, at different peaks intensities of the prepared thin films, compared with those jure and mixeol ZnO ones, spray pyrolysis.
Thin films technology, have many wide scientific application, in the medical field, Lazer technology, Luminscence counters, and at the solar cells fields
There are wide uses of tin oxide thin films, especially in the field of
transparent conductors, solar cells, gas sensors and piezoelectric materials.
Laser deposition is considered one of the most important techniques followed to
obtain these film
s. In this research, we develop a technique to obtain
homogeneous thin films of tin oxide depending on vaporization of pile targets of
this oxide by continuous CO2 laser in the atmosphere, with a fan which
guarantees obtaining homogenous films. Some of these films were annealed in
different conditions. The optical microscope images revealed the presence of
high degree of homogeneity, while the X-Ray study showed different
crystallization grain orientations which depend on the preparation conditions.
The preferred direction is (110). The optical absorption gives information
about the value of the effective band gal for the samples before and after
thermal annealing. We have found that some films have Eg = 3.2 ev. before
annealing, and after long annealing they have Eg=1.3ev. In addition, the hard
annealed thin films reveal anisotropy in the optical and electrical.
Characteristics, they have different absorption coefficients in two
perpendicular directions, also there is an electrical resistance anisotropy along
these two directions especially after hard annealing. The Eb was 0.73 ev before
annealing, it became 0.37 ev for one direction and 0.32 ev for the other
direction.
This research was carried during the period of (2010-2013) to study the possibility of benefiting from the raw seaweeds residuse accumulated on the Syrian beach in obtaining an alternative substrates instead of the traditional one for using in
nurseries, especially forestry, and thus reducing the peat moss importation and saving the currency, at the same time salvation the environment from the organic plant waste and and improve the seashores appearance .
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