Observation of the exciton Mott transition in the photoluminescence of coupled quantum wells
نویسندگان
چکیده
Indirect excitons in coupled quantum wells have long radiative lifetimes and form a cold quasi-two-dimensional population suitable for studying collective quantum effects. Here we report the observation of the exciton Mott transition from an insulating (excitons) to a conducting (ionized electron-hole pairs) phase, which occurs gradually as a function of carrier density and temperature. The transition is inferred from spectral and time-resolved photoluminescence measurements around a carrier density of 2 × 1010 cm−2 and temperatures of 12–16 K. An externally applied electric field is employed to tune the dynamics of the transition via the quantum-confined Stark effect. Our results provide evidence of a gradual nature of the exciton Mott transition.
منابع مشابه
Comment on "Photoluminescence ring formation in coupled quantum wells: excitonic versus ambipolar diffusion".
In a recent Letter [1], an inner ring [2] in the photoluminescence (PL) pattern from GaAs=AlGaAs coupled quantum wells is attributed to the Mott transition in a system of initially photoexcited electron-hole (e-h) pairs and secondary excitons. In contrast, in Ref. [3] the inner ring has been explained and modeled in terms of in-plane transport and thermalization of indirect excitons. In our Com...
متن کاملHigh-energy side-peak emission of exciton-polariton condensates in high density regime
In a standard semiconductor laser, electrons and holes recombine via stimulated emission to emit coherent light, in a process that is far from thermal equilibrium. Exciton-polariton condensates-sharing the same basic device structure as a semiconductor laser, consisting of quantum wells coupled to a microcavity-have been investigated primarily at densities far below the Mott density for signatu...
متن کاملAnomalous transport and luminescence of indirect excitons in AlAs/GaAs coupled quantum wells as evidence for exciton condensation
Due to the long lifetime of indirect ~interwell! excitons, exciton condensation ~analogous to the BoseEinstein condensation of bosons! is expected to occur in coupled quantum wells ~CQW’s!. The critical conditions for the exciton condensation have been predicted to be strongly improved by high magnetic field perpendicular to the well plane. We present results of experimental study of transport ...
متن کاملOptical spectroscopy of neutral and charged excitons in GaAs/AIGaAs quantum wells in high magnetic fields
We implement optical spectroscopy to study charged excitons in modulation-doped GaAs/AIGaAs quantum wells. We report the fLrs~ observation of the positively charged exciton and of the triplet state of the negatively charged exciton. Applyin~g a gate voltage at high magnetic fields, we investigate the transition between metallic and insulating state~ We find that while the photoluminescence fine...
متن کاملHigh-temperature Mott transition in wide-band-gap semiconductor quantum wells
The crossover from an exciton gas to an electron-hole plasma is studied in a GaN/(Al,Ga)N single quantum well by means of combined time-resolved and continuous-wave photoluminescence measurements. The twodimensional Mott transition is found to be of continuous type and to be accompanied by a characteristic modification of the quantum well emission spectrum. Beyond the critical density, the latt...
متن کامل