TY - JOUR
T1 - Observation of Phase-Filling Singularities in the Optical Dielectric Function of Highly Doped n -Type Ge
AU - Xu, Chi
AU - Fernando, Nalin S.
AU - Zollner, Stefan
AU - Kouvetakis, John
AU - Menendez, Jose
N1 - Publisher Copyright:
© 2017 American Physical Society.
PY - 2017/6/27
Y1 - 2017/6/27
N2 - Phase-filling singularities in the optical response function of highly doped (>1019 cm-3) germanium are theoretically predicted and experimentally confirmed using spectroscopic ellipsometry. Contrary to direct-gap semiconductors, which display the well-known Burstein-Moss phenomenology upon doping, the critical point in the joint density of electronic states associated with the partially filled conduction band in n-Ge corresponds to the so-called E1 and E1+Δ1 transitions, which are two-dimensional in character. As a result of this reduced dimensionality, there is no edge shift induced by Pauli blocking. Instead, one observes the "original" critical point (shifted only by band gap renormalization) and an additional feature associated with the level occupation discontinuity at the Fermi level. The experimental observation of this feature is made possible by the recent development of low-temperature, in situ doping techniques that allow the fabrication of highly doped films with exceptionally flat doping profiles.
AB - Phase-filling singularities in the optical response function of highly doped (>1019 cm-3) germanium are theoretically predicted and experimentally confirmed using spectroscopic ellipsometry. Contrary to direct-gap semiconductors, which display the well-known Burstein-Moss phenomenology upon doping, the critical point in the joint density of electronic states associated with the partially filled conduction band in n-Ge corresponds to the so-called E1 and E1+Δ1 transitions, which are two-dimensional in character. As a result of this reduced dimensionality, there is no edge shift induced by Pauli blocking. Instead, one observes the "original" critical point (shifted only by band gap renormalization) and an additional feature associated with the level occupation discontinuity at the Fermi level. The experimental observation of this feature is made possible by the recent development of low-temperature, in situ doping techniques that allow the fabrication of highly doped films with exceptionally flat doping profiles.
UR - http://www.scopus.com/inward/record.url?scp=85021736761&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85021736761&partnerID=8YFLogxK
U2 - 10.1103/PhysRevLett.118.267402
DO - 10.1103/PhysRevLett.118.267402
M3 - Article
C2 - 28707902
AN - SCOPUS:85021736761
SN - 0031-9007
VL - 118
JO - Physical Review Letters
JF - Physical Review Letters
IS - 26
M1 - 267402
ER -