Thin Film Optics Physics of thin film optics

Thin Film Optics • Physics of thin film optics • Important spectral features • Ba. Cu. SF data

Optics basics k wave vector n = index of refraction a = absorption coefficient k = extinction coefficient e = dielectric constant

Bulk sample d Absorption Real sample with surfaces

Thin Film on substrate r 1 n 1=n n 2=s d t 1 r 2 t 2 r 3 t 3 • polarization • angle

Surface reflection and transmission

R & T for real sample(no fringes) surface coeffs multiple bounces

R & T for real sample(w/ fringes)

Deduce Abs Coeff from R & T Transmission normalized to what it “should” have been

Thin Film Interference Fringes n=2. 5, s=1. 5, d=0. 4µm m=2 m=1 Transmission Reflection

Thin Film Interference Fringes n=2. 5, s=1. 5, d=1µm m=7 m=6

Dispersion tightens up fringes n=2. 6+, s=1. 51, d=1µm

Absorption cuts transmission n=2. 6+, s=1. 51, d=1µm, absorption (blue)

Index, absorption model (amorph Si)

Fringes vs angle

Effect of ignoring last surface n=2. 6+, s=1. 51, d=1µm, absorption (blue) red=no substrate, black = w/ substrate

Analysis to find absorption n =2. 6+, s=1. 51, d=1µm blue=abs, red = R+T, black=T/(1 -R)

Determine abs n dispersive, s=1. 51, d=1µm blue=abs, black = T/(1 -R), red=expt abs

Average transmission fringes n dispersive, s=1. 51, d=1µm

Average reflection fringes n dispersive, s=1. 51, d=1µm

Grating Spectrometer

Ba. Cu. SF Transmission

Ba. Cu. SF Gap analysis

Ba. Cu. SF Gap analysis

Ba. Cu. SF R, T Spectra

Ba. Cu. SF Index

Ba. Cu. SF Reflection (th vs expt)

Ba. Cu. SF Transmission (th vs expt)