Dynamics of the phase transitions in the system of nonequilibrium charge carriers in quantum-dimensional Si1 − x Ge x /Si structures

Багаев, В. С.; Кривобок, В. С.; Nikolaev, S. N.; Onishchenko, E. E.; Pruchkina, A. A.; Aminev, D. F.; Skorikov, M. L.; Lobanov, D. N.; Новиков, А. В.

doi:10.1134/s1063776113130074

Cited by 15 publications

(5 citation statements)

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“…This is additionally facilitated by the electric field of nonequilibrium holes accumulating in the QW. As a result, spatially direct two-dimensional excitons and the EHL can form in the alloy layer [13][14][15][16][17][18]. It should be noted that, owing to the accumulation of excitons in the SiGe layer, the excitation-level threshold for the formation of the EHL at a given temperature is considerably lower for the QW than for the Si layers of the structure [12].…”

Section: Condensed Mattermentioning

confidence: 99%

“…Quite recently, an EHL was observed in the quantum wells (QWs) of type-I Si/SiO heterostructures [9][10][11] and type-II Si/SiGe heterostructures with a low Ge content [12][13][14][15][16][17]. 1 It was established that a quasi-two-dimensional EHL is formed in both type-I and type-II structures with sufficiently narrow QWs [10,11,[13][14][15][16][17]. In Si/SiGe structures, the formation of both spatially direct EHL and dipolar EHL with spatially separated electrons and holes is possible [17].…”

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confidence: 99%

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Heating and evaporation of a two-dimensional electron–hole liquid by heat pulses

et al. 2017

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The dynamics of low-temperature ( K) photoluminescence spectra of Si/Si Ge /Si heterostructures ( ) under the influence of a stream of nonequilibrium phonons (heat pulses) propagating in the structure is investigated. The rapid evaporation of the electron-hole liquid in the quantum well of the structure is observed as the liquid is heated by nonequilibrium phonons. It is established that an increase in the exciton-gas density in the quantum well is caused by the evaporation of the electron-hole liquid and by an increase in the rate of exciton capture by the quantum well. It is shown that the interaction with nonequilibrium phonons results in the dissociation of bound-exciton complexes in the Si layers, which is accompanied by an increase in the exciton concentration and lifetime.

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Section: Condensed Mattermentioning

confidence: 99%

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confidence: 99%

Heating and evaporation of a two-dimensional electron–hole liquid by heat pulses

et al. 2017

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“…For the chosen power density of 60 mW/cm 2 , the average distance between excitons in units of their Bohr radius is r s > 2.5. As a rule, this is insufficient for the Mott transition [17,18]. Mean while, for r s < 2, the effect of excitons on each other would already be considerable and could lead to their ionization destruction.…”

Section: Superradiance Of a Degenerate Exciton Gas In Semiconductorsmentioning

confidence: 99%

“…In such QWs, similarly to GaAs/AlGaAs structures [16], local coherence of excitons is possible within large scale fluctuations of a localizing potential caused by the variations of the thickness of the SiGe layer. The details of the sample growth and the setup used for the measurements of photoluminescence (PL) spectra are described, e.g., in [17]. Here, we present the results obtained for a structure containing a 5 nm thick QW with a germa nium content of ~9.5%.…”

Section: Superradiance Of a Degenerate Exciton Gas In Semiconductorsmentioning

confidence: 99%

“…It should be noted that, for indirect gap SiGe/Si QWs, the most prominent fea tures in the 1Eg PL spectra correspond to transverse optical (TO) phonon replicas of the emission lines. Analysis of the spectra in the region of TO replicas makes it possible to isolate the FE and BE lines with an accuracy of ~10-20% of their relative intensities [17].…”

Section: Superradiance Of a Degenerate Exciton Gas In Semiconductorsmentioning

confidence: 99%

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Superradiance of a degenerate exciton gas in semiconductors with indirect fundamental absorption edge

et al. 2014

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In recent years, there has been a surge of interest in the phenomenon of superradiance, which can be observed upon the interaction of a phase locked (coherent) ensemble of emitters with an electromag netic field mode [1][2][3][4][5]. It is well known that one of the consequences of this interaction is the appearance of collective states in which the probability of sponta neous emission is proportional to the square of the number of emitting particles and, thus, is greatly enhanced [6]. To date, the occurrence of superradi ance has been reliably established only for atomic and quasi atomic systems, such as atoms in optical traps [1], quantum dots [7], and J aggregates [8]. At the same time, to the best of our knowledge, the possibility of the formation of superradiant states in a degenerate exciton gas in bulk semiconductors and semiconduc tor quantum wells (QWs) has not been investigated in detail despite considerable progress in attaining the regime of exciton Bose condensation [9,10]. Proba bly, this is related to the fact that the properties of a degenerate exciton gas in semiconductors with a direct fundamental absorption edge are described in terms of strong exciton-photon coupling, and the formalism developed by Dicke [6] cannot be applied. On the other hand, for semiconductors with an indirect absorption edge, the conservation of the quasimomen tum implies that the emission of a photon upon the recombination of an exciton requires either the partic ipation of a phonon or the presence of a short range potential. In this case, the observation of superradi ance is also impossible because the coherence is par tially lost in the final state (i.e., state in which the exci ton ensemble appears after the emission of a photon). Here, we demonstrate that, nevertheless, superradiant states in a system of excitons in an indirect gap semi conductor may be achievable with regard to 2Eg lumi nescence, i.e., the process in which two electron-hole pairs recombine simultaneously with the emission of one photon carrying away their net energy [11,12]. First, we give a qualitative theoretical description of the effect. Next, we present experimental results sup porting the possibility of the observation of superradi ance in SiGe/Si heterostructures.The possibility of the existence of superradiant states can be illustrated in the simplest way by the example of a degenerate gas of noninteracting (or weakly interacting) biexcitons. In a number of semi conductors with an indirect fundamental absorption edge, in particular, in bulk Si [13] or SiGe/Si QWs [14], there are two mechanisms of the radiative recom bination of biexcitons that differ in the number of recombining electron-hole pairs. Conventional (1Eg) luminescence corresponds to the processes in which, upon the emission of a photon by a biexciton, there remains an electron-hole pair. Weak emission with photon energy approximately twice as high as the band gap energy (2Eg luminescence) appears when, upon the simultaneous recombination of the two electronhole pairs comprising ...

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Influence of Boron Selective Doping on the Edge Luminescence of SiGe/Si Quantum Wells

et al. 2015

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Dynamics of the phase transitions in the system of nonequilibrium charge carriers in quantum-dimensional Si1 − x Ge x /Si structures

Cited by 15 publications

References 30 publications

Heating and evaporation of a two-dimensional electron–hole liquid by heat pulses

Heating and evaporation of a two-dimensional electron–hole liquid by heat pulses

Superradiance of a degenerate exciton gas in semiconductors with indirect fundamental absorption edge

Influence of Boron Selective Doping on the Edge Luminescence of SiGe/Si Quantum Wells

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