We report on a method which enables background-free spectroscopy of the narrow absorption lines of shallow impurity transitions in low-doped and high-purity semiconductors, providing a much better spectral resolution than standard Fourier-transform spectrometers. To achieve this, we combined high-resolution continuous-wave terahertz spectroscopy based on a photomixer system with a bandgap excitation scheme for varying the concentration of neutral impurities. For the minority doping species, the lifetime of the excited states can be directly inferred from such a measurement by analyzing the line shape with respect to the width of the lifetime-related Lorentzian contribution. For a germanium sample with residual impurity concentrations of the order 1012 cm−3, we obtained lifetime values of 110 and 130 ps for the 2Γ8 excited state of the acceptors B and Al, respectively. The method complements time-domain pump-probe measurements for moderately and highly doped samples.

1.
E.
Burstein
,
E. E.
Bell
,
J. W.
Davisson
, and
M.
Lax
,
J. Phys. Chem.
57
,
849
(
1953
).
2.
R. L.
Jones
and
P.
Fisher
,
J. Phys. Chem. Solids
26
,
1125
(
1965
).
3.
A. K.
Ramdas
and
S.
Rodriguez
,
Rep. Prog. Phys.
44
,
1297
(
1981
).
4.
S. G.
Pavlov
,
R. K.
Zhukavin
,
E. E.
Orlova
,
V. N.
Shastin
,
A. V.
Kirsanov
,
H.-W.
Hübers
,
K.
Auen
, and
H.
Riemann
,
Phys. Rev. Lett.
84
,
5220
(
2000
).
5.
D.
Karaiskaj
,
J. A. H.
Stotz
,
T.
Meyer
,
M. L. W.
Thewalt
, and
M.
Cardona
,
Phys. Rev. Lett.
90
,
186402
(
2003
).
6.
M.
Cardona
and
M. L. W.
Thewalt
,
Rev. Mod. Phys.
77
,
1173
(
2005
).
7.
N. Q.
Vinh
,
P. T.
Greenland
,
K.
Litvinenko
,
B.
Redlich
,
A. F. G.
van der Meer
,
S. A.
Lynch
,
M.
Warner
,
A. M.
Stoneham
,
G.
Aeppli
,
D. J.
Paul
,
C. R.
Pidgeon
, and
B. N.
Murdin
,
Proc. Natl. Acad. Sci.
105
,
10649
(
2008
).
8.
N. Q.
Vinh
,
B.
Redlich
,
A. F. G.
van der Meer
,
C. R.
Pidgeon
,
P. T.
Greenland
,
S. A.
Lynch
,
G.
Aeppli
, and
B. N.
Murdin
,
Phys. Rev. X
3
,
011019
(
2013
).
9.
N.
Deßmann
,
S. G.
Pavlov
,
V. N.
Shastin
,
R. K.
Zhukavin
,
V. V.
Tsyplenkov
,
S.
Winnerl
,
M.
Mittendorff
,
N. V.
Abrosimov
,
H.
Riemann
, and
H.-W.
Hübers
,
Phys. Rev. B
89
,
035205
(
2014
).
10.
N.
Deßmann
,
S. G.
Pavlov
,
V. V.
Tsyplenkov
,
E. E.
Orlova
,
A.
Pohl
,
V. N.
Shastin
,
R. K.
Zhukavin
,
S.
Winnerl
,
M.
Mittendorff
,
J. M.
Klopf
,
N. V.
Abrosimov
,
H.
Schneider
, and
H.-W.
Hübers
,
Phys. Status Solidi B
254
,
1600803
(
2017
).
11.
H.-W.
Hübers
,
S. G.
Pavlov
,
S. A.
Lynch
,
T.
Greenland
,
K. L.
Litvinenko
,
B.
Murdin
,
B.
Redlich
,
A. F. G.
van der Meer
,
H.
Riemann
,
N. V.
Abrosimov
,
P.
Becker
,
H.-J.
Pohl
,
R. K.
Zhukavin
, and
V. N.
Shastin
,
Phys. Rev. B
88
,
035201
(
2013
).
12.
A. J.
Deninger
,
A.
Roggenbuck
,
S.
Schindler
, and
S.
Preu
,
J. Infrared, Millimeter Terahertz Waves
36
,
269
(
2015
).
13.
K. L.
Litvinenko
,
E. T.
Bowyer
,
P. T.
Greenland
,
N.
Stavrias
,
J.
Li
,
R.
Gwilliam
,
B. J.
Villis
,
G.
Matmon
,
M. L. Y.
Pang
,
B.
Redlich
,
A. F. G.
van der Meer
,
C. R.
Pidgeon
,
G.
Aeppli
, and
B. N.
Murdin
,
Nat. Commun.
6
,
6549
(
2015
).
14.
M.
Steger
,
A.
Yang
,
D.
Karaiskaj
,
M. L. W.
Thewalt
,
E. E.
Haller
,
J. W.
Ager
,
M.
Cardona
,
H.
Riemann
,
N. V.
Abrosimov
,
A. V.
Gusev
,
A. D.
Bulanov
,
A. K.
Kaliteevskii
,
O. N.
Godisov
,
P.
Becker
, and
H.-J.
Pohl
,
Phys. Rev. B
79
,
205210
(
2009
).
15.
B. A.
Andreev
,
E. B.
Kozlov
, and
T. M.
Lifshits
,
Mater. Sci. Forum
196–201
,
121
(
1995
).
16.
P.
Kühne
,
N.
Armakavicius
,
V.
Stanishev
,
C. M.
Herzinger
,
M.
Schubert
, and
V.
Darakchieva
,
IEEE Trans. Terahertz Sci. Technol.
8
,
257
(
2018
).
17.
M. S.
Skolnick
,
L.
Eaves
, and
R. A.
Stradling
,
Solid State Commun.
15
,
1403
(
1974
).
18.
M.
Cardona
,
Modulation Spectroscopy: Solid State Physics
(
Academic Press
,
New York
,
1969
), Vol.
S11
.
19.
M.
Lax
,
Phys. Rev.
119
,
1502
(
1960
).
20.
E.
Rotsaert
,
P.
Clauws
,
J.
Vennik
, and
L.
Van Goethem
,
J. Appl. Phys.
65
,
730
(
1989
).
21.

Technically, the apparent FTIR cut-off frequency is increased in Fig. 3(b) by the involved apodization and zero-padding.

22.
B.
Pajot
,
Optical Absorption and Defects in Semiconductiong Crystals
(
Springer
,
Berlin
,
2010
), Vol.
1
.
23.
T.
Alam
,
M.
Wienold
,
X.
,
K.
Biermann
,
L.
Schrottke
,
H. T.
Grahn
, and
H.-W.
Hübers
,
Opt. Express
27
,
5420
(
2019
).
You do not currently have access to this content.