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Martínez, Javier López; Martínez, Gerardo; Torres‐Delgado, G.; Guzmán, Octavio Gómez; Ángel, P. Del; Zelaya-Ángel, O.; Lozada‐Morales, R.

doi:10.1023/a:1018555826924

Cited by 15 publications

(9 citation statements)

References 7 publications

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“…Details of the growth process have been described in a previous work [4]. Thickness of films measured using a Dektak II profilometer was 200 ± 10 nm.…”

Section: Methodsmentioning

confidence: 99%

Effects of annealing on the lattice parameter of polycrystalline CdS thin films

Lozada‐Morales¹,

Zelaya-Ángel

2004

Cryst. Res. Technol.

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Cubic CdS (β-CdS) polycrystalline thin films were prepared on glass substrates by chemical synthesis at 80 °C. Samples were subjected to thermal treatments (TT) in the range of temperatures (T) 180 -500 °C during 30 hours in different ambients. Annealing in air and in H 2 produces in CdS larger lattice parameter enlargements (≤ 2.5 %) when T of TT increases up to T ≤ 500 °C. Whereas, annealing in Ar + S 2 and vacuum provokes intermediate (≤ 1.2 %) and smaller (≤ 0.9 %) maxima values of the lattice parameter increments, respectively. Energy band gap (E g ) as a function of T of TT and as a function of the lattice parameter has been also studied where it was observed that E g behaves in very different manners depending on the ambient chosen for annealing.

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“…Details of the growth process have been described in a previous work [4]. Thickness of films measured using a Dektak II profilometer was 200 ± 10 nm.…”

Section: Methodsmentioning

confidence: 99%

Effects of annealing on the lattice parameter of polycrystalline CdS thin films

Lozada‐Morales¹,

Zelaya-Ángel

2004

Cryst. Res. Technol.

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“…The CBD method used to grow the CdSe layers was described elsewhere [17]. The substrates employed were glass-slides, which were cleaned by immersing them into an aqueous solution of K 2 Cr 2 O 7 , diluted in concentrated HCl, during 24 h. Afterwards, they were rubbed using distilled water and free Na detergent, rinsed in deionized water and then blow-dried using filtered clean air.…”

Section: Methodsmentioning

confidence: 99%

Quantum Confinement and Crystalline Structure of CdSe Nanocrystalline Films

Rivera-Márquez¹,

Rubín‐Falfán

Lozada‐Morales

et al. 2001

phys. stat. sol. (a)

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Nanocrystalline CdSe films were grown onto glass substrates by the chemical bath method. Different constant deposition temperatures (T d ) were employed in the range 4-65 ºC. Average grain size (GS) increased monotonically with T d , reaching saturation at~65 ºC. The GS values were in the interval 5-16 nm. At low T d values (4-15 ºC), the structural phase was hexagonal wurtzite (W), for intermediate values, a wurtzite and zincblende (ZB) mixture of phases was found, and at high T d (65 ºC) only cubic ZB phase was present in the layers. The variation of the bandgap as a result of the structural phase change and quantum confinement is studied.

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“…Thus, stoichiometric thin films of CdSe in cubic phase were obtained similar to CdS with the same structural symmetry using the CBD technique. 13 Band structure analysis from optical absorption data evidenced two critical points at 1.84 and 2.2 eV, respectively. Theoretical calculations of band structure of cubic modification of CdSe do not predict the existence of this last electronic transition; 14,15 however, the recent experimental data of dielectric function in cubic CdSe reveal a spin-orbit split of 0.41 eV in accordance with our results.…”

mentioning

confidence: 98%

Properties of CdSe Polycrystalline Thin Films Grown by Chemical Bath

Lozada‐Morales

Rubín‐Falfán

Portillo-Moreno

et al. 1999

J. Electrochem. Soc.

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Semiconducting CdSe films have been continuously studied as a photoconductive material 1,2 for their importance in photovoltaic energy conversion, 3,4 and lately, for their noticeable quantum confinement effect properties. [5][6][7][8] Wurtzite is the stable phase of CdSe, and the sphalerite CdSe modification is a metastable structural phase. In spite of the relatively abundant works published in CdSe thin films, this material is the least studied II-VI compound in thin-film format, especially for cubic CdSe. Many physical properties of cubic CdSe remain as unconcluded studies, for instance, band structure and phonon dispersion, among others. By using new deposition techniques like molecular beam epitaxy, 9 laser ablation, 10 electrochemical atomic layer, 11 etc., it has been possible to grow CdSe in cubic phase with a wide variety of changing growth conditions. In this way, a lot of information has been gained recently for a better understanding of the physical properties of thin films of this material.In this work the chemical bath deposition (CBD) technique was used to prepare polycrystalline CdSe thin films on glass substrates having about 200 nm thickness. Although this technique has been already used to grow this material, 1,2,12 the optical and electrical properties usually depend upon the growing parameters such as temperature, stirring, chemical agents, and concentrations during the grown process. Thus, stoichiometric thin films of CdSe in cubic phase were obtained similar to CdS with the same structural symmetry using the CBD technique. 13 Band structure analysis from optical absorption data evidenced two critical points at 1.84 and 2.2 eV, respectively. Theoretical calculations of band structure of cubic modification of CdSe do not predict the existence of this last electronic transition; 14,15 however, the recent experimental data of dielectric function in cubic CdSe reveal a spin-orbit split of 0.41 eV in accordance with our results. 16 Dark conductivity (DC) measurements in the 100-500 K range showed the presence of a high density of deep levels that promotes the carrier conduction described by the Mott's variable range hopping (VRH) model. After this first round of DC measurements, two consecutive rounds, in the same range of temperature, were carried out. Then the high density of deep levels disappeared and the conductivity was dominated by a thermally activated process following Arrhenius behavior. The crystalline quality of the films improved already after the first cycle of measurements, as this acted like a thermal annealing.

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Untitled

Cited by 15 publications

References 7 publications

Effects of annealing on the lattice parameter of polycrystalline CdS thin films

Effects of annealing on the lattice parameter of polycrystalline CdS thin films

Quantum Confinement and Crystalline Structure of CdSe Nanocrystalline Films

Properties of CdSe Polycrystalline Thin Films Grown by Chemical Bath

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