Comparative study of the negatively and positively charged excitons in GaAs quantum wells

Abstract

We compare the photoluminescence spectra of the negatively and positively charged excitons in GaAs quantum wells. We use a structure which enables us to observe both complexes within the same sample. We find that their binding energy and Zeeman splitting are very similar at zero magnetic field, but evolve very differently at high fields. We discuss the implications of these observations on our understanding of the charge excitons structure in high magnetic fields. ͓S0163-1829͑99͒51516-6͔

Positively charged magnetoexcitons in a semiconductor quantum well

“…4. Moreover this result is also in agreement with the experimental results which showed that the energy of the X + is larger 13,14 or equal 19 to the one of X − . Stébé and Moradi 6 found, on the other hand, that for a 300Å wide quantum well the binding energy of X + is lower than the one of X − which is opposite to our conclusion and to those of Ref.…”

“…3, we compare the binding energy of the X + and of the X − singlet state for a 200Å wide quantum well with the experimental results obtained by Glasberg et al 19 and the very recent results Yusa et al 24 (open triangles). When comparing the experimental results with our theoretical results we notice that for B = 0 the experimental and theoretical result for the negatively charged exciton binding energy differ by about 0.3 meV, which may be due to a non-zero density effect and/or to localization induced by quantum well width fluctuation.…”

“…In spite of the large number of theoretical [1][2][3][4][5][6][7][8][9][10][11] and experimental [12][13][14][15][16][17][18][19][20][21][22][23] works published in recent years on the subject of charged excitons in quantum wells, only a very small number of them deals with positively charged excitons 4,6,10,14,16,18,19 . Different authors 4,18 used the diffusion Monte Carlo technique to calculate the dependence of the binding energy of the positively charged exciton on the well width at zero magnetic field.…”

Effects of an electron gas on the negative trion in semiconductor quantum wells

“…This makes the observation of the X − a difficult task only recently achieved in high-quality samples. Since its first observation [3], the trion has been intensively studied, both experimentally [4] and theoretically [5]. One of the aspects that has not been considered yet is the influence of the excess of electrons in the trion properties.…”

Charged Excitons in the Quantum Hall Regime

“…However, one of the striking differences of optical experiments, compared to transport, is the presence of photoexcited holes in the system, which can significantly influence its properties. In samples with very low carrier concentration, the Coulomb interaction between electrons and holes leads to the formation of negatively charged excitons, which have been a subject of intense research during the past decade (see, e.g., [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22]). For samples with relatively strong disorder, the commonly accepted picture is that at low density the two-dimensional electron system (2DES) breaks up into areas with finite density (electron puddles) and completely depleted regions, where neutral excitons (X 0 ) can form.…”