Spatially Resolved Thermodynamics of the Partially Ionized Exciton Gas in GaAs

Bieker, S.; Henn, T.; Kießling, T.; Ossau, W.; Molenkamp, L. W.

doi:10.1103/physrevlett.114.227402

Cited by 15 publications

(9 citation statements)

References 25 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Figure 7(a) displays a phase-diagram of the coupled free carrier/exciton system in GaN as predicted by the law of mass action, or Saha equation. 12,[70][71][72] The diagram depicts the fraction of electron-hole pairs f x = n x /n eh forming excitons, with the total density of cathodogenerated electronhole pairs n eh . The density of unbound, free carriers is then given by ∆n = ∆p = (1 − f x ) n eh .…”

Section: Temperature Dependence Of L and D: Exciton Diffusionmentioning

confidence: 99%

“…In particular, in several cases it has been found to be essential to take into account exciton a) Electronic mail: oliver.brandt@pdi-berlin.de b) Present address: Istituto per la Microelettronica e Microsistemi, Consiglio Nazionale delle Ricerche, via del Fosso del Cavaliere 100, 00133 Roma, Italy formation. [4][5][6][7][8][9][10][11][12][13][14][15] In materials with high exciton binding energies such as diamond, [13][14][15] exciton diffusion may profoundly modify the carrier diffusivity even at elevated temperatures and high carrier densities. Given the exciton binding energy of 26 meV in GaN, we would expect exciton diffusion to play an important role in this material as well.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Carrier diffusion in GaN -- a cathodoluminescence study. II: Ambipolar vs. exciton diffusion

Brandt,

Kaganer,

Lähnemann

et al. 2020

Preprint

View full text Add to dashboard Cite

We determine the diffusion length of excess carriers in GaN by spatially resolved cathodoluminescence spectroscopy utilizing a single quantum well as carrier collector or carrier sink. Monochromatic intensity profiles across the quantum well are recorded for temperatures between 10 and 300 K. A classical diffusion model accounts for the profiles acquired between 120 and 300 K, while for temperatures lower than 120 K, a quantum capture process has to be taken into account in addition. Combining the diffusion length extracted from these profiles and the effective carrier lifetime measured by time-resolved photoluminescence experiments, we deduce the carrier diffusivity as a function of temperature. The experimental values are found to be close to theoretical ones for the ambipolar diffusivity of free carriers limited only by intrinsic phonon scattering. This agreement is shown to be fortuitous. The high diffusivity at low temperatures instead originates from an increasing participation of excitons in the diffusion process.

show abstract

Section: Temperature Dependence Of L and D: Exciton Diffusionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Carrier diffusion in GaN -- a cathodoluminescence study. II: Ambipolar vs. exciton diffusion

Brandt,

Kaganer,

Lähnemann

et al. 2020

Preprint

View full text Add to dashboard Cite

show abstract

“…It has previously been shown that the Saha equation allows for a precise description of the spatially dependent population balance of the partially ionized exciton gas under continuous-wave laser excitation in bulk [19] and of the time evolution of the exciton gas in semiconductor quantum wells [7,20]. We here demonstrate that the experimental free exciton TRPL traces in bulk GaAs, and in particular the slow photoluminescence rise, is also consistently described by the shift of the thermodynamic ionization equilibrium from the uncorrelated electron-hole plasma (EHP) to the free exciton state.…”

mentioning

confidence: 99%

Thermodynamic origin of the slow free exciton photoluminescence rise in GaAs

et al. 2016

Self Cite

View full text Add to dashboard Cite

We use time-resolved photoluminescence (TRPL) spectroscopy to unequivocally clarify the microscopic origin of the nanosecond free exciton photoluminescence rise in GaAs at low temperatures. In crucial distinction from previous work, we examine the TRPL of the GaAs free exciton second LO-phonon replica. This enables us to simultaneously monitor the unambiguous time evolution of the total exciton population and the cooling dynamics of the initially hot free exciton ensemble. We demonstrate by a model based on the Saha equation and the experimentally determined cooling behavior that the long-debated slow photoluminescence rise is caused by time-dependent shifts in the thermodynamic quasiequilibrium between free excitons and the uncorrelated electron-hole plasma.

show abstract

“…The bare mass of the free exciton is m x = m n +m p , and we assume that the difference between the bare and effective exciton mass-defined as the inverse curvature of an excitonic band close to its minimumis negligible . The analogue of the Saha's equation for semiconductors reads [39,40]…”

Section: Exciton Dissociation Equilibriummentioning

confidence: 99%

An excitonic model for the electron–hole plasma relaxation in proton-irradiated insulators

et al. 2021

View full text Add to dashboard Cite

The relaxation of free electron–hole pairs generated after proton irradiation is modelled by means of a simplified set of hydrodynamic equations. The model describes the coupled evolution of the electron–hole pair and self-trapped exciton (STE) densities, along with the electronic and lattice temperatures. The equilibration of the electronic and lattice excitations is based on the two-temperature model, while two mechanisms for the relaxation of free electron–hole pairs are considered: STE formation and Auger recombination. Coulomb screening and band gap renormalisation are also taken into account. Our numerical results show an ultrafast ($${\ll }\,{\mathrm {1}}$$ ≪ 1 ps) free electron–hole pair relaxation time in amorphous $${{\mathrm {SiO}}_{\mathrm {2}}}$$ SiO 2 for initial carrier densities either below or above the exciton Mott transition. Coulomb screening alone is not found to yield the long relaxation time ($${\mathrm {\gg }}{\mathrm {10}}$$ ≫ 10 ps) experimentally observed in amorphous $${{\mathrm {SiO}}_{\mathrm {2}}}$$ SiO 2 and borosilicate crown glass BK7 irradiated with high-intensity laser pulses or BK7 irradiated by short proton pulses. Another mechanism, e.g. thermal detrapping of STEs, is required to correctly model the long free electron–hole pair relaxation time observed experimentally. Graphical Abstract

show abstract

Spatially Resolved Thermodynamics of the Partially Ionized Exciton Gas in GaAs

Cited by 15 publications

References 25 publications

Carrier diffusion in GaN -- a cathodoluminescence study. II: Ambipolar vs. exciton diffusion

Carrier diffusion in GaN -- a cathodoluminescence study. II: Ambipolar vs. exciton diffusion

Thermodynamic origin of the slow free exciton photoluminescence rise in GaAs

An excitonic model for the electron–hole plasma relaxation in proton-irradiated insulators

Contact Info

Product

Resources

About