thin films (see bowen & tanner, high resolution x-ray diffractometry and topography, chap. 3)...
TRANSCRIPT
Thin films(see Bowen & Tanner, High Resolution X-ray Diffractometry and Topography, Chap. 3)
Thin films(see Bowen & Tanner, High Resolution X-ray Diffractometry and Topography, Chap. 3)
Common epilayer defectsCommon epilayer defects
Thin films(see Bowen & Tanner, High Resolution X-ray Diffractometry and Topography, Chap. 3)
Thin films(see Bowen & Tanner, High Resolution X-ray Diffractometry and Topography, Chap. 3)
Common epilayer defects
Investigate using rocking curves
Common epilayer defects
Investigate using rocking curves
Thin films(see Bowen & Tanner, High Resolution X-ray Diffractometry and Topography, Chap. 3)
Thin films(see Bowen & Tanner, High Resolution X-ray Diffractometry and Topography, Chap. 3)
Common epilayer defects
Investigate using rocking curves
Layer & substrate peaks split
rotation invariant
Common epilayer defects
Investigate using rocking curves
Layer & substrate peaks split
rotation invariant
Thin filmsThin films
Common epilayer defects
Investigate using rocking curves
Layer & substrate peaks split
varies w/rotation
Common epilayer defects
Investigate using rocking curves
Layer & substrate peaks split
varies w/rotation
Thin filmsThin films
Common epilayer defects
Investigate using rocking curves
Broadens layer peakinvariant w/ beam sizepeak position invariant
w/ sample position
Common epilayer defects
Investigate using rocking curves
Broadens layer peakinvariant w/ beam sizepeak position invariant
w/ sample position
Thin filmsThin films
Common epilayer defects
Investigate using rocking curves
Broadens layer peakmay increase w/ beam
sizepeak position invariant
w/ sample position
Common epilayer defects
Investigate using rocking curves
Broadens layer peakmay increase w/ beam
sizepeak position invariant
w/ sample position
Thin filmsThin films
Common epilayer defects
Investigate using rocking curves
Broadens layer peakincreases w/ beam sizepeak position varies
w/ sample position
Common epilayer defects
Investigate using rocking curves
Broadens layer peakincreases w/ beam sizepeak position varies
w/ sample position
Thin filmsThin films
Common epilayer defects
Investigate using rocking curves
Layer & substrate peaks split splitting different for
symmetric & asymmetric reflections
Common epilayer defects
Investigate using rocking curves
Layer & substrate peaks split splitting different for
symmetric & asymmetric reflections
Thin filmsThin films
Common epilayer defects
Investigate using rocking curves
Various effects vary w/ sample position
Common epilayer defects
Investigate using rocking curves
Various effects vary w/ sample position
Thin filmsThin films
Investigate using rocking curves
Film thickness
Integrated intensity changesincreases w/ thickness
Interference fringes
Investigate using rocking curves
Film thickness
Integrated intensity changesincreases w/ thickness
Interference fringes
Thin filmsThin films
MismatchMismatch
constrained relaxed
Thin filmsThin films
Mismatch
Layer & substrate peaks split – rotation invariant
Measure, say, (004) peak separation , from which
d/d = – cot = m* (mismatch)
Mismatch
Layer & substrate peaks split – rotation invariant
Measure, say, (004) peak separation , from which
d/d = – cot = m* (mismatch)
constrained relaxed
Thin filmsThin films
Misorientation
First, determine orientation of substrate
rotate to bring plane normal into counter plane
do scans at this positionand at + 180°
orientation angle = 1/2difference in two angles
Misorientation
First, determine orientation of substrate
rotate to bring plane normal into counter plane
do scans at this positionand at + 180°
orientation angle = 1/2difference in two angles
= 90°
Thin filmsThin films
Misorientation
First, determine orientation of substrate
Layer tilt (assume small)
layer peak shifts w/ in scans
Misorientation
First, determine orientation of substrate
Layer tilt (assume small)
layer peak shifts w/ in scans
= 90°
shift +
Thin filmsThin films
Misorientation
First, determine orientation of substrate
Layer tilt (assume small)
layer peak shifts w/ in scans
Misorientation
First, determine orientation of substrate
Layer tilt (assume small)
layer peak shifts w/ in scans
= 90°
shift –
Thin filmsThin films
Misorientation
First, determine orientation of substrate
Layer tilt (assume small)
layer peak shifts w/ in scans
Misorientation
First, determine orientation of substrate
Layer tilt (assume small)
layer peak shifts w/ in scans
= 90°
no shift
Thin filmsThin films
Misorientation
First, determine orientation of substrate
Layer tilt (assume small)
layer peak shifts w/ in scans
Misorientation
First, determine orientation of substrate
Layer tilt (assume small)
layer peak shifts w/ in scans
= 90°
no shift
Thin filmsThin films
Dislocations
From:high mismatch strain, locally relaxedlocal plastic deformation due to straingrowth dislocations
Dislocations
From:high mismatch strain, locally relaxedlocal plastic deformation due to straingrowth dislocations
Thin filmsThin films
Dislocations
From:high mismatch strain, locally relaxedlocal plastic deformation due to straingrowth dislocations
Estimate dislocation density from broadening (radians)
& Burgers vector b (cm):
= 2/9b2
Dislocations
From:high mismatch strain, locally relaxedlocal plastic deformation due to straingrowth dislocations
Estimate dislocation density from broadening (radians)
& Burgers vector b (cm):
= 2/9b2
Thin filmsThin films
Curvature
R = radius of curvature, s = beam diameter
angular broadening = s/R =
beam radius broadening
5 mm 100 m 10"
Curvature
R = radius of curvature, s = beam diameter
angular broadening = s/R =
beam radius broadening
5 mm 100 m 10"
Thin filmsThin films
Relaxation
Need to measure misfit parallel to interface
Both mismatch &misorientation changeon relaxation
Interplanar spacings change with mismatch distortion & relaxation – changes splittings
Relaxation
Need to measure misfit parallel to interface
Both mismatch &misorientation changeon relaxation
Interplanar spacings change with mismatch distortion & relaxation – changes splittings
Thin filmsThin films
Relaxation
Need to measure misfit parallel to interface
Both mismatch &misorientation changeon relaxation
So, also need misfit perpendicular to interface
Then, % relaxation is
Relaxation
Need to measure misfit parallel to interface
Both mismatch &misorientation changeon relaxation
So, also need misfit perpendicular to interface
Then, % relaxation is
Thin filmsThin films
Relaxation
Grazing incidence Incidence angle usually
very low….~1-2°
Limits penetration ofspecimen
Relaxation
Grazing incidence Incidence angle usually
very low….~1-2°
Limits penetration ofspecimen
reflectingplane
Thin filmsThin films
Relaxation
Grazing incidence Incidence angle usually
very low….~1-2°
Limits penetration ofspecimen
Penetration depth – G(x) = fraction of total diffracted intensity from layer x cm thick compared to infinitely thick specimen
Relaxation
Grazing incidence Incidence angle usually
very low….~1-2°
Limits penetration ofspecimen
Penetration depth – G(x) = fraction of total diffracted intensity from layer x cm thick compared to infinitely thick specimen
Thin filmsThin films
Relaxation
Grazing incidence Incidence angle usually
very low….~1-2°
Limits penetration ofspecimen
Penetration depth – G(x) = fraction of total diffracted intensity from layer x cm thick compared to infinitely thick specimen
Relaxation
Grazing incidence Incidence angle usually
very low….~1-2°
Limits penetration ofspecimen
Penetration depth – G(x) = fraction of total diffracted intensity from layer x cm thick compared to infinitely thick specimen
Thin filmsThin films
Relaxation
Grazing incidence Incidence angle usually
very low….~1-2°
Reflection not fromplanes parallel to specimen surface
Relaxation
Grazing incidence Incidence angle usually
very low….~1-2°
Reflection not fromplanes parallel to specimen surface
reflectingplane
Thin filmsThin films
Relaxation
Grazing incidence If incidence angle ~0.1-5° & intensity measured in
symmetric geometry (incident angle = reflected angle),
get reflectivity curve
Relaxation
Grazing incidence If incidence angle ~0.1-5° & intensity measured in
symmetric geometry (incident angle = reflected angle),
get reflectivity curve
Thin filmsThin films
Relaxation
Need to measure misfit parallel to interface
Use grazing incidencee.g., (224) or (113)
Relaxation
Need to measure misfit parallel to interface
Use grazing incidencee.g., (224) or (113)
Thin filmsThin films
Relaxation
Use grazing incidencee.g., (224) or (113)
Need to separate tiltfrom true splitting
Tilt effect reversedon rotation of = 180°
Mismatch splittingunchanged on rotation
Relaxation
Use grazing incidencee.g., (224) or (113)
Need to separate tiltfrom true splitting
Tilt effect reversedon rotation of = 180°
Mismatch splittingunchanged on rotation
Thin filmsThin films
Relaxation
Use grazing incidencee.g, (224) or (113)
For grazing incidence:
i = +
– splitting betwn substrate & layer
Relaxation
Use grazing incidencee.g, (224) or (113)
For grazing incidence:
i = +
– splitting betwn substrate & layer
Thin filmsThin films
Relaxation
Use grazing incidencee.g, (224) or (113)
For grazing incidence:
i = +
e = –
Can thus get bothand
Relaxation
Use grazing incidencee.g, (224) or (113)
For grazing incidence:
i = +
e = –
Can thus get bothand
Thin filmsThin films
Relaxation
Also,
And
Relaxation
Also,
And
Thin filmsThin films
Relaxation
Also,
And
Finally
Relaxation
Also,
And
Finally
Thin filmsThin films
Homogeneity
Measure any significant parameter over a grid on specimen
Ex: compositional variation
get composition using Vegards lawmeasure lattice parameter(s) – calculate relaxed
mismatch
Homogeneity
Measure any significant parameter over a grid on specimen
Ex: compositional variation
get composition using Vegards lawmeasure lattice parameter(s) – calculate relaxed
mismatch
Thin filmsThin films
Homogeneity
Measure any significant parameter over a grid on specimen
Ex: variation of In content in InAlAs layer on GaAs
Homogeneity
Measure any significant parameter over a grid on specimen
Ex: variation of In content in InAlAs layer on GaAs
Thin filmsThin films
Thickness
For simple structure layer, layer peak integrated intensity increases monotonically w/ thickness
Thickness
For simple structure layer, layer peak integrated intensity increases monotonically w/ thickness
calculated curvescalculated curves
Thin filmsThin films
Thickness
For simple structure layer, layer peak integrated intensity increases monotonically w/ thickness
Note thickness fringes
Can use to estimatethickness
Thickness
For simple structure layer, layer peak integrated intensity increases monotonically w/ thickness
Note thickness fringes
Can use to estimatethickness
calculated curvescalculated curves
Thin filmsThin films
Thickness
For simple structure layer, layer peak integrated intensity increases monotonically w/ thickness
Thickness
For simple structure layer, layer peak integrated intensity increases monotonically w/ thickness
calculated curvescalculated curves