In Situ Studies of the Microstructure of a-Si:H Surfaces and Interfaces
- PDF / 370,797 Bytes
- 6 Pages / 420.48 x 639 pts Page_size
- 115 Downloads / 197 Views
OF a-Si:H SURFACES AND INTERFACES
IN SITU STUDIES OF THE MICROSTRUCTURE
R.W. COLLINS The Standard Oil Company, Rd., Cleveland, OH 44128
Corporate
Research Center,
4440 Warrensville Center
ABSTRACT Using in situ ellipsometry with a 3.4 eV probe, we have characterized the initial nucleation and interface structure of a-Si:H and #c-Si deposited on oxide/c-Si substrates. Multilayered a-Si:H/a-SiN :H structures have also been studied and non-uniformities have been modeled. XIn none of the reported data could we model thin film growth with thickness independent optical functions. is very sensitive to changes in the ellipsometry Once a film becomes opaque, layers. As a result, roughness on single and thickness of surface roughness as well as the renucleation that multilayered a-Si:H films has been studied results from stopping and then restarting the a-Si:H growth plasma.
INTRODUCTION In situ ellipsometry studies by Hottier and Theeten[1] and Drevillon[2] in characterizing the a-Si:H nucleation and growth have proven effective is used, the experiment is extremely process. When a near ultraviolet probe sensitive to initial nucleation and to changes in surface microstructure after The dielectric function of a-Si:H in this range the film has become opaque. provides information on the packing density of Si-Si bonds.[3] We have applied ellipsometry to study a wider range of problems dealing with the structure of interfaces between amorphous materials. We can determine how very thin films (• 100 9) differ from thick films prepared under the same conditions owing to an incompletely developed microstructure. This is important in devices and for the interpretation of for the optimization of thin layers the optical properties of amorphous multilayer materials.[4]
EXPERIMENTAL TECHNIQUE AND DATA ANALYSIS To obtain the data, an rf glow discharge reactor was mounted at the axis of a spectroscopic rotating analyzer ellipsometer set for a 70° angle of incidence.[5] The substrates were mounted at the cathode; we are in the process of studying anode depositions as well. During deposition, a 20-cycle average of light intensity was obtained every the Fourier coefficients of the reflected 2.5 sec. The ellipsometry angles # and A were obtained from the Fourier coefficients using calibration procedures and analysis described elsewhere.[6] functions
Data Loading...
