Mechanism of terahertz lasing in SiGe/Si quantum wells

Blom, Anders; Odnoblyudov, M. A.; Cheng, Huang; Yassievich, I. N.; Chao, K. A.

doi:10.1063/1.1389769

Cited by 29 publications

(21 citation statements)

References 11 publications

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“…The resonant acceptor state is created when the energy splitting between the ground and split-off acceptor states exceeds the binding energy. In the case of Si 1-x Ge x structures, the splitting energy of the valence subbands is about 31 meV [7]. According to variational calculations, the binding energy of shallow acceptors is about 27 meV; the same value was obtained [7] for the energy difference between the split-off acceptor state and the edge of higher-energy valence subband.…”

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confidence: 63%

“…In the case of Si 1-x Ge x structures, the splitting energy of the valence subbands is about 31 meV [7]. According to variational calculations, the binding energy of shallow acceptors is about 27 meV; the same value was obtained [7] for the energy difference between the split-off acceptor state and the edge of higher-energy valence subband. Thus, one can expect that the internal strain in the Si 1-x Ge x layer is sufficient for the split-off state to become resonant.…”

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confidence: 63%

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THz lasing of SiGe/Si quantum‐well structures due to shallow acceptors

Kagan

Алтухов

Chirkova

et al. 2002

Physica Status Solidi (b)

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An intense THz emission was observed from strained SiGe/Si quantum-well structures under strong pulsed electric field. The p-type structures were MBE-grown on n-type Si substrates and δ-doped with boron. Lines with wavelengths near 100 microns were observed in the emission spectrum. The modal structure in the spectrum gave evidence for the stimulated nature of the emission. The origin of the THz emission was attributed to intra-centre optical transitions between resonant and localized boron levels.

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mentioning

confidence: 63%

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confidence: 63%

THz lasing of SiGe/Si quantum‐well structures due to shallow acceptors

Kagan

Алтухов

Chirkova

et al. 2002

Physica Status Solidi (b)

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show abstract

“…According to variational calculations, the binding energy of shallow acceptors is about 27 meV. The same value was obtained [9] for the energy difference between the split-off acceptor state and the edge of higher-energy valence subband. Thus, one can expect that the internal strain in the Si 1-x Ge x layer is sufficient for the split-off state to become resonant.…”

Section: Compressed P-gementioning

confidence: 79%

“…A resonant acceptor state is created when the energy splitting between the ground and split-off acceptor states exceeds the binding energy. For Si 1-x Ge x structures with x = 0.15, the splitting energy of the valence subbands is about 31 meV [9]. According to variational calculations, the binding energy of shallow acceptors is about 27 meV.…”

Section: Compressed P-gementioning

confidence: 99%

THz lasing due to resonant acceptor states in strained p‐Ge and SiGe quantum‐well structures

Kagan

Алтухов

Chirkova

et al. 2003

Physica Status Solidi (b)

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An intense THz emission was observed from strained SiGe/Si quantum-well structures under a strong pulsed electric field. The p-type structures were MBE-grown on n-type Si substrates and δ-doped with boron. Lines with wavelengths near 100 microns were observed in the emission spectrum. The modal structure in the spectrum gave evidence for the stimulated nature of the emission. The origin of the THz emission was attributed to intra-center optical transitions between resonant and localized boron levels similar to that in compressed p-Ge.Introduction Recently, activity towards the quantum cascade THz laser on the basis of SiGe/Si heterostructures has started [1]. Here we discuss the possibility to create an alternative type of THz laser source which could utilize a much simpler quantum well (QW) structure, i.e. a resonant-state laser (RSL) [2,3]. Population inversion in the RSL is realized for the states of a shallow acceptor split under external uniaxial stress. If the strain is high enough (above ≈3 kbar for Ge), the split-off acceptor state enters the light-hole branch of the valence band and creates a resonant state [4]. An applied electric field depopulates the localized impurity states due to impact ionization. A population inversion of resonant states with respect to the impurity states in the gap is then formed [5] and THz lasing occurs.The resonant states can appear for different reasons, e.g., they should exist in Si 1-x Ge x /Si structures which are strained internally due to the lattice mismatch. Acceptor-doped Si 1-x Ge x is very attractive for fabricating the RSL because of its good thermal properties, low absorption in the THz range, well established, relatively cheap technology, as well as possible integration with Si-based electronics.

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“…Calculations showed that this energy is about 27 meV [3,4]. On the other hand, the Fermi level is close to the QW valence band edge and the free hole concentration at equilibrium conditions is of the order of the acceptor concentration in the QW [5,6]. That is why the population inversion should be difficult to reach even if impact ionization could occur.…”

Section: Introductionmentioning

confidence: 98%