Photoluminescence of inversion electrons with carbon acceptors in a single modulation-doped Al<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mrow /><mml:mi>x</mml:mi></mml:msub></mml:math>Ga<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mrow /><mml:mrow><mml:mn>1</mml:mn><mml:mo>−</mml:mo><mml:mi>x</mml:mi></mml:mrow></mml:msub></mml:math>As/GaAs heterostructure

The photoluminescence of an electron inversion layer with a monolayer of carbon acceptors in GaAs was investigated at liquid helium temperatures. In the limit of high laser illumination the luminescence line approaches a hat shape, the expected form if the recombination center is a single isolated acceptor. At medium illumination the line takes on a trapezoidal form, and in the small illumination limit a triangular shape emerges. The line shape variations could be traced back to the interaction of the carbon acceptors which is ruled by the illumination strength. Acceptor-acceptor interactions spread the distribution of transition energies and initiate a transfer of oscillator strength. The triangular line shape at low illumination is a clear signature of an impurity band formed in the carbon monolayer.

Section: Introductionmentioning

confidence: 98%

Influence of recombination center interaction on the photoluminescence of AlGaAs/GaAs heterostructures

Schuster

Kim

Batke

et al. 2013

“…Our n-modulation doped Al 0.35 Ga 0.65 As-GaAs single heterostructures have an overall standard design [5][6][7][8][9] as shown in figure 1(a). Counted from the top of a semi-insulating (100) GaAs substrate there is a dislocation barrier, a 624 nm GaAs buffer, a 105 nm Al 0.35 Ga 0.65 As layer and a homogeneously n-doped 5 nm GaAs cap.…”

Section: Methodsmentioning

confidence: 99%

“…where T is a universal electron temperature valid for both subbands. Equation (7) assumes thermal equilibrium between the subbands and the Fermi-Energy is counted with respect to the ground subband optical gap E g0 .…”

Section: + Expmentioning

confidence: 99%

Two-dimensional electron bound hole photoluminescence in GaAs in perpendicular magnetic fields

Schuster¹,

Kim²,

Batke³

et al. 2020

The photoluminescence of quasi two-dimensional (2D) electrons in modulation doped Al x Ga 1 − x As-GaAs single heterostructure recombining with bound holes was studied at liquid helium temperatures in magnetic fields up to 9 T. Luminescence contributions from the ground and a weakly populated first excited 2D subband were observed as well as bulk-like contributions from the GaAs buffer. The 2D subband and the bulk signals are linked and oscillate with the magnetic field strength. It is not the filling factor that rules but the alignment of the two subband Landau-ladders paired with intersubband scattering that drives an oscillatory behavior of the subband populations. Asymmetric Landau-level transition line shapes indicate a perturbed 2D electron system. We performed a detailed analyses of Landau-level dependent line strengths, positions and half widths and compared the experiment with calculations of subband energies and transition matrix elements. The total electron density is not fixed in our experiment but decreases with magnetic field strength. This might indicate that the 2D system exchanges electrons with a reservoir and/or that the correlation between radiative and nonradiative recombination channels vary strongly with the magnetic field strength.

“…Our n-modulation doped Al 1−x Ga x As-GaAs single heterostructures have an overall standard design [14][15][16][17] as shown in figure 1. Counted from the top of a semi-insulating (100) GaAs substrate there is a dislocation barrier, a 624nm GaAs buffer, a 105nm Al 0.35 Ga 0.65 As layer and a homogeneously n-doped 5nm GaAs cap.…”

Section: Methodsmentioning

confidence: 99%

“…Experimental profiles approaching the ideal limit can be found at the higher excitation intensities, e.g., 158 and 390mW cm −2 in figure 5(b). The deviations can be traced back to disorder, recombination center interactions and a transition probability dependent on 2D wave vector [15][16][17]. The subband optical gaps for both subbands are shown in figures 5(a) and (b) by downward pointing arrows and vertical dotted lines, respectively.…”

Section: Magnetotransport In the Persistent Photoeffect Regimementioning

confidence: 99%

Interlayer charge transfer in n-modulation doped Al_1−xGa_xAs–GaAs single heterostructures

Schuster

Kim

Batke

et al. 2018

We studied the interlayer charge transfer in n-modulation doped Al 1−x Ga x As-GaAs single heterostructures by photoluminescence and magnetotransport. Photoluminescence contributions from a high-mobility quasi-twodimensional electron system at the interface and GaAs bulk type excitons were analyzed, covering an excitation intensity range of nearly three orders of magnitude. The experiment was compared with selfconsistent band structure calculations that allowed to follow the charge redistribution in the sample. After sample cool down in the dark a parallel conducting quasi-twodimensional channel of low electron mobility appeared in the Al 1−x Ga x As-layer, that gained in density up to a saturation value. There was only little interaction between the Al 1−x Ga x As and GaAs sides in the persistent regime and a reduction of the depletion charge in the GaAs could largely account for the interface channel density enhancement. Contrary, the negative photoeffect present during continuous illumination strongly depends on the interaction between the interface and the parallel channel, which serves as a temporary sink for excess charges from the GaAs side. When the illumination is switched off the parallel channel acts as a source and the sample essentially returns to the prior illumination state of saturation.