دراسة الخواص التركيبية والخواص البصرية الخطية واللاخطية لأغشية أشباه الموصلات CdS و CdSe و CdS/CdSe

الباحث

برزان خلف قاسم

المشرف

إرادة عبدالخالق خليل - محمد محمود يونس

الجامعة

جامعة الموصل

الكلية / القسم

كلية العلوم / قسم الفيزياء

الشهادة

ماجستير

السنة

2023

لغة الرسالة

عربي

الكلمات المفتاحية

أشباه الموصلات ; الأغشية الرقيقة ; الخواص البصرية اللاخطية ; كبريتيد الكادميوم

In this work, the effect of a number of factors on the optical and structural properties of thin films prepared from cadmium sulfide (CdS), cadmium selenide (CdSe) and CdSe/CdSe on glass bases was studied using a thermal chemical spray system. Thin films of CdS were prepared on glass substrates by chemical spray pyrolysis method from solutions including different concentrations of Na2S (0.2 and 0.4 gm) with (0.3 gm) of cadmium chloride. Scanning electron microscopy and X-ray spectroscopy showed a clear change in thestructural properties and grain size of the prepared films with the change of concentration of Na2S sodium sulfide, as the grain size increases with increasing Na2S concentration, and the average grain size ranges from 8.993 nm to 39.57 nm for the films prepared at a concentration of 0.2gm. of Na2S and while it changed from 80 nm to 300 nm for the films prepared with a concentration of 0.4gm of Na2S, the effect of changing the concentration of Na2S in the prepared solutions was also shown on the properties, optical constants and energy gap of the prepared films clearly as it was observed that the energy gap increases with concentration.Thin films of CdS have been deposited on glass bases using the chemical thermal spray technique by mixing different concentrations of cadmium chloride(CdCl2, 0.4, 0.3, 0.2 gm) with (0.4 gm) of sodium sulfide Na2S. Scanning electron microscopy images and X-ray spectrum showed that the grain size increased with the increase in concentration, as the average grain size at the concentration (0.2gm) was around (14 nm) and the grain size increased to (23 nm) at the concentration (0.3 gm), then the grain size became (0.3 gm). (100 nm) at a concentration of (0.4 gm), the change of CdCl2 concentration in the preparation of the thin films has a clear effect on their optical properties. Thin films of CdS cadmium sulphide were prepared from a solution containing (0.4 gm) of Na2S and (0.3gm) of CdCl2 at different temperatures (250,200,150,100 oC). Electron microscopy images showed that the grain size decreases with increasing temperature and that the average grain size ranges from 54 nm for the films prepared at 100 oC to 17 nm for the films prepared at 250 oC and this is consistent with the X-ray spectrum, that the change in the optical properties and the value of the energy gap is a reflection For the clear change in electron microscopy images and particle sizes, it was observed that the energy gap decreases with increasing temperature. And we used bases of glass as a basis for the deposition of cadmium selenide films, as the deposition was done at a temperature of 50,100,150oC,the scanning electron microscope images and X-ray spectrum showed that the size of the grains decreased with the temperature, as the size of the grains ranged between (219.5 -132.3 nm), either The average particle size was around (175.9 nm), and we also found that the optical properties decreased with increasing wavelength, while theenergy gap changed from (2.2-1.7 eV).Electron microscope images showed a significant change in the structural properties of two samples of cadmium sulfide and selenide junction deposited on glass bases, where the cadmium sulfide films prepared from 20 sprays were distinguished, while the cadmium selenide films were deposited with a different number of sprinkles, the scanning electron microscopy images show that the films are amorphous, It also shows that the grain size of CdS was about 80 nm and about 200 nm for CdSe due to the low deposition temperature, while the grain size became about 300 nm for CdSe/CdS. It is worth noting that the energy gap also changed and we found that the energy gap was 2.2 electron volts for the film. CdS and 1.7 eV for the CdSe film while it became 1.8 eV for the CdSe/CdS .The nonlinear optical properties of cadmium selenide and cadmium sulfide were studied at different temperatures, and we noticed that the absorption coefficient and refractive index decrease with increasing temperature.

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