Non‐hydrogenated amorphous germanium carbide with adjustable microstructure and properties: a potential anti‐reflection and protective coating for infrared windows

Abstract

Amorphous non-hydrogenated germanium carbide (a-Ge 1Àx C x ) films have been deposited using magnetron co-sputtering technique by varying the sputtering power of germanium target (P Ge ). The effects of P Ge on composition and structure of the a-Ge 1Àx C x films have been analyzed. The FTIR spectrum shows that the C-Ge bonds were formed in the a-Ge 1Àx C x films according to the absorption peak at~610 cm À1 . The Raman results indicate that the amorphous films also contain both Ge and C clusters. The XPS results reveal that the carbon concentration decreased as P Ge increased from 40 to 160 W. The fraction of sp 3 C-C bonds remains almost constant when increasing P Ge from 40 to 160 W. The sp 2 C-C content of a-Ge 1Àx C x film decreases gradually to 35.9% with P Ge up to 160 W. Nevertheless, sp 3 C-Ge sites rose with increasing P Ge . Furthermore, the hardness and the refractive index gradually increased with increasing P Ge . The excellent optical transmission of annealed a-Ge 1-x C x double-layer coating at 400 C suggests that a-Ge 1Àx C x films can be used as an effective anti-reflection coating for the ZnS IR window in the wavelength region of 8-12 mm, and can endure higher temperature than hydrogenated amorphous germanium carbide do.

On the Origin of Reduced Cytotoxicity of Germanium-Doped Diamond-Like Carbon: Role of Top Surface Composition and Bonding

“…A peak-fit of the C 1s and Ge 3d spectra recorded from the undoped DLC and Ge-doped DLC layers is illustrated. The C 1s envelopes indicate the following bonding states: The spectral intensity at 283.3 eV, ascribed to C−Ge [22][23][24][25][26]; at 284.3 eV, ascribed to C sp 2 ; at 285.2 eV, ascribed to C sp 3 [23,[27][28][29][30]; at 286.5 eV, ascribed to C−O; at 287.9 eV, ascribed to C=O [21,31]; at 288.7 eV, ascribed to the π−π* shake up satellite [30]. The Ge 3d envelope indicates the following bonding states: The spectral intensity at 29.3 eV, ascribed to Ge-Ge [25,26]; at 30.2 eV, ascribed to Ge−C [22,25]; at 31.2 eV, ascribed to GeO [32,33]; at 32.7 eV, ascribed to GeO 2 [32,33].…”

Effect of deposition parameters on the microstructure and deposition rate of germanium-carbon coatings prepared by plasma enhanced chemical vapor deposition

“…Although up to now, some properties of germanium-carbon coatings prepared by the different method such as plasma enhanced chemical vapor deposition (PECVD) [8][9][10][11], X-ray chemical vapor deposition [12,13], RF co-sputtering [14][15][16], and RF reactive sputtering [17][18][19][20] have been studied, but such limited investigations are not enough for development of these coatings. Moreover, most researches have been conducted on structural and bonding characteristics of germanium-carbon coatings, but microscopic characterization of these coatings have not been fully investigated so far.…”

Hardness and optical gap enhancement of germanium carbon films by nitrogen incorporation

“…Germanium carbon films have attracted much attention because of their excellent properties: low stress, low light absorption, good adhesion on many far-infrared substrates, etc. This makes them promising candidate for application as antireflective and protective coatings (APC) on far-infrared windows [2,3]. However, there are two problems associated with germanium carbon films as APC.…”