Difference between microstructures and optical properties of Pb1-xGexTe thin films evaporated using different deposition methods

作者：Xie Ping^*; Li Bin; Zhang Suying; Liu Dingquan

来源：Acta Optica Sinica, 2012, 32(SUPPL.1).

DOI：10.3788/AOS201232.s131002

• Coating material
• Columnar microstructures
• Deposition methods
• Electron beam evaporation
• Electron beam heating
• Energy dispersive x-ray analysis (EDX)
• Extinction coefficients
• Ge content
• Germanium telluride
• Granular size
• High Index materials
• High-index
• Mechanically robust
• Narrow-gap semiconductors
• Optical transparency
• PbTe
• Pseudo-binaries
• Resistance-heating
• Silicon substrates
• Source material
• Spectral range
• Transmission spectrums

Lead germanium telluride (Pb1-xGexTe), a pseudo-binary alloy of IV-VI narrow gap semiconductors PbTe and GeTe, is considered as a potential mechanically robust high-index coating material. Pb1-xGexTe thin films are evaporated on silicon substrates from the ingots of single crystals using electron-beam and resistance heating, respectively. The surface topographies and compositions of thin films are characterized using scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX), and the transmission spectra in a spectral range from 2.5 m to 12 μm are also examined. Thin films demonstrates columnar microstructure. Moreover, those evaporated using electron beam heating have Ge content closer to one in source material, much larger granular dimensions, and higher refractive index and extinction coefficient in comparison with those using resistance heating. Accordingly, the electron beam evaporation has the advantage of keeping the complex semiconductor material stoichiometric. It can be concluded that the stoichiometric consistency and large granular size of the electron beam evaporation films have higher refractive index. It can be deduced the scattering from the larger grains may impair the optical transparency of the films.

• 出版日期2012