Propriedades estruturais do nitreto de germanio amorfo hidrogenado : (a-GeNx:H)

AUTOR(ES)
DATA DE PUBLICAÇÃO

1994

RESUMO

In this work we report optical and structural properties of hydrogenated germanium nitrogen alloys (a-GeNx:H). These films were prepared by the rf-reactive sputtering technique, using a crystalline germanium target in Argon + Ammonia or Argon + Nitrogen + Hydrogen (or Deuterium) atmosphere. Its properties are strongly dependent on the deposition parameters. The band gap ranges from approximately 1 eV to 3 eV by just changing the applied power. The deposition temperature also plays an important role in its structural properties. Deuterium was used to replace the hydrogen in the films in order to distinguish the infrared absorption bands related to the vibrations of the alloy elements bonded to hydrogen. The spectrum obtained for a-GeNx:H deposited in the 150 ºC to 300 ºC range shows absorption bands characteristic of Ge-N, Ge-H, N-H, N-H2 vibrations. In the a-GeNx:D films the hydrogen atoms are replaced by deuterium atoms and the corresponding Ge-D, N-D, and N-D2 absorption bands are shifted to lower energy .The shifting of frequencies are consistent with the D to H-atom mass ratio factor. A shifting of the bands associated with hydrogen as the nitrogen concentration changes has also been observed. The films prepared at room temperature show spontaneous atmospheric contamination, which tends to saturate after a few months. Several absorption bands appear in the 2700-3800 cm-1 range and at 1400-1650 cm-1. In order to assign those absorption bands, a systematic analysis has been performed using the evolution of the infrared spectra as the atmosphere exposing time increases. Stress measurements were performed in samples prepared in different deposition conditions. The thermal expansion coefficient and the Young modulus as a function of nitrogen concentration was also measured

ASSUNTO(S)

semicondutores amorfos - propriedades oticas espectroscopia de infravermelho

ACESSO AO ARTIGO

Documentos Relacionados