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Title: Band offsets for biaxially and uniaxially stressed silicon-germanium layers with arbitrary substrate and channel orientations

Abstract

The conduction and valence band offsets between a strained silicon-germanium layer and a silicon-germanium substrate are reported for arbitrary substrate and channel crystal orientations. The offsets are calculated both for the case of biaxial stress, corresponding approximately to the stress state of a thin strained channel in a planar field-effect transistor (FET), and for uniaxial stress, which is the approximate stress state for strained channels in a FinFET configuration. Significant orientation dependence is found for the conduction band offset, overall leading to the strongest electron quantum confinement in biaxial-tensile stressed channels on {100}-oriented substrates, and uniaxial-tensile stressed channels in the 〈100〉 and 〈110〉 directions. For biaxially stressed layers on {111} substrates, the conduction band offset is significantly smaller than for {100} or {110} directions. For the valence band offset, the dependence on crystal orientation is found to be small.

Authors:
; ; ; ; ;  [1]
  1. Imec, Kapeldreef 75, 3001 Heverlee (Belgium)
Publication Date:
OSTI Identifier:
22597739
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 120; Journal Issue: 5; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; CONFINEMENT; CRYSTALS; ELECTRONS; FIELD EFFECT TRANSISTORS; GERMANIUM; LAYERS; SILICON; STRAINS; STRESSES; SUBSTRATES; VALENCE

Citation Formats

Eneman, Geert, Roussel, Philippe, Brunco, David Paul, Collaert, Nadine, Mocuta, Anda, and Thean, Aaron. Band offsets for biaxially and uniaxially stressed silicon-germanium layers with arbitrary substrate and channel orientations. United States: N. p., 2016. Web. doi:10.1063/1.4960140.
Eneman, Geert, Roussel, Philippe, Brunco, David Paul, Collaert, Nadine, Mocuta, Anda, & Thean, Aaron. Band offsets for biaxially and uniaxially stressed silicon-germanium layers with arbitrary substrate and channel orientations. United States. doi:10.1063/1.4960140.
Eneman, Geert, Roussel, Philippe, Brunco, David Paul, Collaert, Nadine, Mocuta, Anda, and Thean, Aaron. Sun . "Band offsets for biaxially and uniaxially stressed silicon-germanium layers with arbitrary substrate and channel orientations". United States. doi:10.1063/1.4960140.
@article{osti_22597739,
title = {Band offsets for biaxially and uniaxially stressed silicon-germanium layers with arbitrary substrate and channel orientations},
author = {Eneman, Geert and Roussel, Philippe and Brunco, David Paul and Collaert, Nadine and Mocuta, Anda and Thean, Aaron},
abstractNote = {The conduction and valence band offsets between a strained silicon-germanium layer and a silicon-germanium substrate are reported for arbitrary substrate and channel crystal orientations. The offsets are calculated both for the case of biaxial stress, corresponding approximately to the stress state of a thin strained channel in a planar field-effect transistor (FET), and for uniaxial stress, which is the approximate stress state for strained channels in a FinFET configuration. Significant orientation dependence is found for the conduction band offset, overall leading to the strongest electron quantum confinement in biaxial-tensile stressed channels on {100}-oriented substrates, and uniaxial-tensile stressed channels in the 〈100〉 and 〈110〉 directions. For biaxially stressed layers on {111} substrates, the conduction band offset is significantly smaller than for {100} or {110} directions. For the valence band offset, the dependence on crystal orientation is found to be small.},
doi = {10.1063/1.4960140},
journal = {Journal of Applied Physics},
number = 5,
volume = 120,
place = {United States},
year = {Sun Aug 07 00:00:00 EDT 2016},
month = {Sun Aug 07 00:00:00 EDT 2016}
}
  • No abstract prepared.
  • We have studied uniaxially stressed Ge doped with Cu, a substitutional triple acceptor, by photoconductivity spectroscopy. We find that the ground state of this triple acceptor, normally accommodating three 1[ital s] holes, reconfigures into an atomic Li-like 1[ital s][sup 2] 2[ital s][sup 1] arrangement by the application of [100] stress. Above 4 kbar the first ionization potential reaches a constant value of 17.4 meV corresponding to the hole excitation from the now partially occupied 2[ital s] energy level. Excellent agreement was obtained between the experimental results and variational calculations.
  • The influence of uniaxial stress on the extrinsic photoconductivity of gallium-doped germanium has been investigated. It has been found that the long-wavelength cutoff is shifted from 114 ..mu..m for zero stress to 200 ..mu..m for a uniaxial stress of 6.6 x 10/sup 3/ kg/cm/sup 2/ along a (100) direction. At this value of stress the responsivity was approx.2 x 10/sup 4/ V/W and the NEP was approx.2 x 10/sup -11/ W/Hz/sup 1/2/ at 190 ..mu..m.
  • Iron-acceptor pair defects in silicon are insensitive to stress. These defects therefore provide convenient reference points from which to measure the effects of uniaxial stress on the valence-band structure in silicon. Despite the strong mixing of light- and heavy-hole bands at low values of stress, we find that for thermal emission the stress-split valence band can be approximated as two independent bands that displace rigidly with increasing stress according to the shear deformation potentials. The spherical approximation for the effective masses is not consistent with these deformation potentials because the approximation incorrectly partitions the density of states between the twomore » bands. We establish the correct partitioning of the density of states numerically, and find stress-dependent density of states that approximately conserve the center of gravity of the split valence bands. Uniaxial stress data on the Fe-Al defects in silicon are used to experimentally verify the numerical results. The analysis described in this paper can be easily generalized to determine the stress properties of hole traps in any p-type semiconductor.« less
  • The effects of the terahertz-stimulated emission of Group-V donors (phosphorus, antimony, arsenic, bismuth) in uniaxially stressed silicon, excited by CO{sub 2} laser radiation are experimentally studied. It is shown that uniaxial compressive stress of the crystal along the [100] direction increases the gain and efficiency of stimulated radiation, significantly decreasing the threshold pump intensity. The donor frequencies are measured and active transitions are identified in stressed silicon. The dependence of the residual population of active donor states on the uniaxial compressive stress along the [100] direction is theoretically estimated.