AFM Morphology Study of Si1-Y GeY:H Films Deposited by LF PE CVD from Silane-Germane with Different Dilution

Abstract

AbstractThe morphology of Si1-Y GeY:H films in the range of Y=0.23 to 0.9 has been studied by AFM. The films were deposited by Low Frequency (LF) PE CVD at substrate temperature Ts=300 C and discharge frequency f=110 kHz from silane+germane mixture with and without, Ar and H2 dilution. The films were deposited on silicon and glass substrates. AFM images were taken and analyzed for 2x2 μm2 area. All the images demonstrated “grain” like structure, which was characterized by the height distribution function F(H) average roughness <H>, standard height deviation Rq, lateral correlation length Lc, area distribution function F(s), mean grain area <s>, diameter distribution function F(d), and mean grain diameter <d>. The roughness <H> of the films monotonically increases with Y for all dilutions, but more significantly in the films deposited without dilution. Lc continuously grows with Y in the films deposited without dilution, while more complex behavior of Lc(Y) is observed in the films deposited with H- or Ar dilution. The sharpness of F(H) characterized by curtosis γ depends on dilution, and the sharpest F(H) are for the films deposited with Ar ( γ=5.30,Y=0.23) and without dilution (γ=4.3, Y=0.45). Isothermal annealing caused an increase of <H>, Lc in the films deposited with H- and Ar dilutions, while in the films prepared without dilution the behavior was more complex, depending on the substrates. After the annealing a significant sharpening of the height distributions, F(H), was observed in the films deposited with H dilution or without dilution.