Forbidden energy band gap in diluted a-Ge1 − xSix:N films |
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Authors: | C. GuarnerosB. Rebollo-Plata R. Lozada-Morales J.E. Espinosa-RosalesJ. Portillo-Moreno O. Zelaya-Angel |
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Affiliation: | a Posgrado en Física Aplicada, Facultad de Ciencias Físico-Matemáticas, Benemérita Universidad Autónoma de Puebla, Blvd. 14 Sur 6301, Col. San Manuel, 72570, Puebla, Mexicob Facultad de Ciencias Químicas, Benemérita Universidad Autónoma de Puebla, Blvd. 14 Sur 6301, Col. San Manuel, 72570, Puebla, Mexicoc Departamento de Física, Centro de Investigación y de Estudios Avanzados del IPN, PO Box 14-740, México 07360 D.F., Mexico |
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Abstract: | By means of electron gun evaporation Ge1 − xSix:N thin films, in the entire range 0 ≤ x ≤ 1, were prepared on Si (100) and glass substrates. The initial vacuum reached was 6.6 × 10− 4 Pa, then a pressure of 2.7 × 10− 2 Pa of high purity N2 was introduced into the chamber. The deposition time was 4 min. Crucible-substrate distance was 18 cm. X-ray diffraction patterns indicate that all the films were amorphous (a-Ge1 − xSix:N). The nitrogen concentration was of the order of 1 at% for all the films. From optical absorption spectra data and by using the Tauc method the energy band gap (Eg) was calculated. The Raman spectra only reveal the presence of SiSi, GeGe, and SiGe bonds. Nevertheless, infrared spectra demonstrate the existence of SiN and GeN bonds. The forbidden energy band gap (Eg) as a function of x in the entire range 0 ≤ x ≤ 1 shows two well defined regions: 0 ≤ x ≤ 0.67 and 0.67 ≤ x ≤ 1, due to two different behaviors of the band gap, where for x > 0.67 exists an abruptly change of Eg(x). In this case Eg(x) versus x is different to the variation of Eg in a-Ge1 − xSix and a-Ge1 − xSix:H. This fact can be related to the formation of Ge3N4 and GeSi2N4 when x ≤ 0.67, and to the formation of Si3N4 and GeSi2N4 for 0.67 ≤ x. |
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Keywords: | Si 0" alt=" single bond" src=" http://cdn.els-cdn.com/sd/entities/sbnd" class=" glyphImg" >Ge alloys Optical properties Amorphous Energy band gap |
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