Screening of excitonic states by low-density 2D charge carriers in GaAs/AlGaAs quantum wells

Optical method for the determination of carrier density in modulation-doped quantum wells

“…is to use the method based on dimensional magnetoplasma resonance [12]. This method requires high mobility of the carriers and has been successfully applied for III-V heterostructures only.…”

Cyclotron resonance of composite fermions with two and four flux quanta

“…2 p + (! cr =2) 2 ] 1=2 [12,13]. As it is clear from Figs Illustration of the optical scheme to detect resonant microwave absorption for the electron cyclotron-magnetoplasmon hybrid mode at low B-ÿelds.…”

“…cr = eB=m * -dependence. Further details of the electron cyclotron resonance are discussed elsewhere [12]. Additional support for the validity of the detection method comes from a comparison with the measurements based on the conventional approach using a bolometer (see Fig.…”

“…The development of an optical luminescence detection scheme [12] that boosts the sensitivity to resonant microwave absorption was a prerequisite for our studies. Several high-quality GaAs=Al 0:3 Ga 0:7 As heterostructures, containing a single 30 nm wide quantum well, served the investigation.…”

“…Several high-quality GaAs=Al 0:3 Ga 0:7 As heterostructures, containing a single 30 nm wide quantum well, served the investigation. The embedded 2DES, with carrier densities and electron transport mobilities between 0.6 -1:5 × 10 11 =cm 2 and 3-5×10 6 cm 2 =V s respectively, were patterned into disks with a diameter of 1 mm [12]. The samples were placed near the end of a 16-or 8-mm short-circuited waveguide in the electric ÿeld maximum of the microwave excitation inside a He 3 cryostat with a 12 T magnet.…”