Post on 08-Mar-2020
Rui Vilão – University of Coimbra
Semiconductors: a μSR approach
ISIS muon spectroscopy training school
March/2012
Semiconductors: a SR approach
Rui Vilão – University of Coimbra
Semiconductors: a μSR approach
ISIS muon spectroscopy training school
March/2012
Outline
• What’s the point? H in semiconductors
• Muonium/Hydrogen: the basic Si story
• Beyond Si: Levels, levels, levels
• Other Mu/H related stuff
Rui Vilão – University of Coimbra
Semiconductors: a μSR approach
ISIS muon spectroscopy training school
March/2012
Semiconductors: materials with extreme sensibility to the
presence of impurities and defects
Rui Vilão – University of Coimbra
Semiconductors: a μSR approach
ISIS muon spectroscopy training school
March/2012
H – common (unavoidable impurity)
Mostly passivating other impurities... ...rarely activating
Rui Vilão – University of Coimbra
Semiconductors: a μSR approach
ISIS muon spectroscopy training school
March/2012
When isolated, H is most commonly a compensating impurity
Rui Vilão – University of Coimbra
Semiconductors: a μSR approach
ISIS muon spectroscopy training school
March/2012
...but it can be electrically active in some cases
Rui Vilão – University of Coimbra
Semiconductors: a μSR approach
ISIS muon spectroscopy training school
March/2012
Muonium: a privileged tool to investigate isolated
hydrogen and, ocasionally, hydrogen complexes
Mu – light pseudo-isotope of H
Not for weak-hearted
particle physicists!
Rui Vilão – University of Coimbra
Semiconductors: a μSR approach
ISIS muon spectroscopy training school
March/2012
Rui Vilão – University of Coimbra
Semiconductors: a μSR approach
ISIS muon spectroscopy training school
March/2012
Rui Vilão – University of Coimbra
Semiconductors: a μSR approach
ISIS muon spectroscopy training school
March/2012
Isotropic Mu first observed in quartz and germanium...
2-FREQUENCY PRECESSION OF MUONIUM IN A MAGNETIC FIELD
GUREVICH, II; IVANTER, IG; MELESHKO, EA, et al.
SOVIET PHYSICS JETP-USSR 33, 253 (1971)
...and then in silicon
Rui Vilão – University of Coimbra
Semiconductors: a μSR approach
ISIS muon spectroscopy training school
March/2012
Rui Vilão – University of Coimbra
Semiconductors: a μSR approach
ISIS muon spectroscopy training school
March/2012
Rui Vilão – University of Coimbra
Semiconductors: a μSR approach
ISIS muon spectroscopy training school
March/2012
Rui Vilão – University of Coimbra
Semiconductors: a μSR approach
ISIS muon spectroscopy training school
March/2012
Rui Vilão – University of Coimbra
Semiconductors: a μSR approach
ISIS muon spectroscopy training school
March/2012
Rui Vilão – University of Coimbra
Semiconductors: a μSR approach
ISIS muon spectroscopy training school
March/2012
10-5
10-4
10-3
10-2
10-1
100
101
102
0,0
0,1
0,2
0,3
0,4
0,5
a23
and a14
a12
and a34
A = 3454.26 M H z
Pre
cess
ion
am
pli
tud
es
B (T )
Rui Vilão – University of Coimbra
Semiconductors: a μSR approach
ISIS muon spectroscopy training school
March/2012
Muonium was first identified in Si by longitudinal-field quenching
The spectroscopic measurements had a surprise:
Rui Vilão – University of Coimbra
Semiconductors: a μSR approach
ISIS muon spectroscopy training school
March/2012
Rui Vilão – University of Coimbra
Semiconductors: a μSR approach
ISIS muon spectroscopy training school
March/2012
Rui Vilão – University of Coimbra
Semiconductors: a μSR approach
ISIS muon spectroscopy training school
March/2012
Rui Vilão – University of Coimbra
Semiconductors: a μSR approach
ISIS muon spectroscopy training school
March/2012
We now have a rather complete model for Mu/H in Si
For further developments:
Rui Vilão – University of Coimbra
Semiconductors: a μSR approach
ISIS muon spectroscopy training school
March/2012
S. F. J. Cox
ISIS Muon Training
Course 2008
Getting the levels…
Rui Vilão – University of Coimbra
Semiconductors: a μSR approach
ISIS muon spectroscopy training school
March/2012
Simple ways for determining
the levels
1. Phenomenological Boltzmann functions
Rui Vilão – University of Coimbra
Semiconductors: a μSR approach
ISIS muon spectroscopy training school
March/2012
2. Conversion between Mu states: a simple approach
Rui Vilão – University of Coimbra
Semiconductors: a μSR approach
ISIS muon spectroscopy training school
March/2012
3. Spin-charge exchange dynamics probed in longitudinal fields
Rui Vilão – University of Coimbra
Semiconductors: a μSR approach
ISIS muon spectroscopy training school
March/2012
H/Mu in silicon – a compensating impurity
Rui Vilão – University of Coimbra
Semiconductors: a μSR approach
ISIS muon spectroscopy training school
March/2012
…also in Ge and SiGe,…
Rui Vilão – University of Coimbra
Semiconductors: a μSR approach
ISIS muon spectroscopy training school
March/2012
…and diamond…
Rui Vilão – University of Coimbra
Semiconductors: a μSR approach
ISIS muon spectroscopy training school
March/2012
... and in GaAs, ZnSe, ZnS
Rui Vilão – University of Coimbra
Semiconductors: a μSR approach
ISIS muon spectroscopy training school
March/2012
However, in CdS, an hydrogenic state is observed
Rui Vilão – University of Coimbra
Semiconductors: a μSR approach
ISIS muon spectroscopy training school
March/2012
...and in ZnO
Rui Vilão – University of Coimbra
Semiconductors: a μSR approach
ISIS muon spectroscopy training school
March/2012
Rui Vilão – University of Coimbra
Semiconductors: a μSR approach
ISIS muon spectroscopy training school
March/2012
Rui Vilão – University of Coimbra
Semiconductors: a μSR approach
ISIS muon spectroscopy training school
March/2012
ZnO
ZnSe
(+/-)
H behaving as a dopant
(donor)
H behaving as a compensating
centre (amphoteric impurity
always contradicting
conductivity) CG Van de Walle, Phys Stat Solidi (b) 229 (2002) 221
Rui Vilão – University of Coimbra
Semiconductors: a μSR approach
ISIS muon spectroscopy training school
March/2012
(+/-) predicted to be
constant
A key to the problem: band line-ups!
Rui Vilão – University of Coimbra
Semiconductors: a μSR approach
ISIS muon spectroscopy training school
March/2012
Rui Vilão – University of Coimbra
Semiconductors: a μSR approach
ISIS muon spectroscopy training school
March/2012
Hydrogen as a source
of conductivity in
oxides
+/- pinning level at 3.0 0.4 eV
Rui Vilão – University of Coimbra
Semiconductors: a μSR approach
ISIS muon spectroscopy training school
March/2012
Rui Vilão – University of Coimbra
Semiconductors: a μSR approach
ISIS muon spectroscopy training school
March/2012
Rui Vilão – University of Coimbra
Semiconductors: a μSR approach
ISIS muon spectroscopy training school
March/2012
Deep acceptors No muonium is seen Shallow donors
(also In2O3, Ga2O3)
? ? ? Deep donors (Ag2O and
HgO, not represented)
? ?
Rui Vilão – University of Coimbra
Semiconductors: a μSR approach
ISIS muon spectroscopy training school
March/2012
Shallow donor hydrogen in
transparent conductive oxides
Rui Vilão – University of Coimbra
Semiconductors: a μSR approach
ISIS muon spectroscopy training school
March/2012
Oxides: the devil hides in the details
Rui Vilão – University of Coimbra
Semiconductors: a μSR approach
ISIS muon spectroscopy training school
March/2012
Oxides: the devil hides in the details
Y2O3 E. Silva et al.,
arXiv:1106.5032v1 [cond-mat.mtrl-sci], 2011.
Rui Vilão – University of Coimbra
Semiconductors: a μSR approach
ISIS muon spectroscopy training school
March/2012
Other stuff: I. Muon diffusion and defect/impurities passivation
Rui Vilão – University of Coimbra
Semiconductors: a μSR approach
ISIS muon spectroscopy training school
March/2012
Other stuff: I. Muon diffusion and defect/impurities passivation
Rui Vilão – University of Coimbra
Semiconductors: a μSR approach
ISIS muon spectroscopy training school
March/2012
Other stuff: II. An organic glimpse
Rui Vilão – University of Coimbra
Semiconductors: a μSR approach
ISIS muon spectroscopy training school
March/2012
Other stuff: III. Electron spin polarization
Rui Vilão – University of Coimbra
Semiconductors: a μSR approach
ISIS muon spectroscopy training school
March/2012