Magnetophotoluminescence study of theGa0.5In0.5P/G

Abstract

We studied two-dimensional properties of electrons accumulated at the GaAs side of Ga 0.5 In 0.5 P/GaAs-single heterointerface. Long-range ordering in Ga 0.5 In 0.5 P causes the electron accumulation at the GaAs side of the heterointerface. Photoluminescence ͑PL͒ spectra of GaAs have been systematically measured for undoped unordered and ordered Ga 0.5 In 0.5 P/GaAs samples. A PL spectrum of the ordered sample shows signals related to the quantized electron state in a triangular potential buried at the heterointerface and the Fermi-edge singularity, in contrast that the unordered sample shows a typical PL spectrum of a high-quality bulk GaAs. Magneto-PL spectra indicate that the reduced exciton masses between parallel and perpendicular to the heterointerface are anisotropic. We found clear optical Shubnikov-de Haas ͑SdH͒ oscillations in both the PL intensity and the transition energy under the perpendicular magnetic field. These PL features demonstrate that the electrons accumulated at the heterointerface act as two-dimensional electron gas ͑2DEG͒. The sheet-carrier density of the 2DEG is deduced from the period of the observed SdH oscillation and it found to be ϳ1.20 ϫ10 12 cm Ϫ2 .

Photoluminescence upconversion atGaAs/InGaP2interfaces driven by a sequential two-photon absorption mechanism

“…We observe a broad luminescence peak centered on 1.520 eV, which is consistent with reported emission energies for band edge recombination in bulk n-type GaAs [30,31]. We additionally observe a high-energy shoulder to this peak at about 1.560 eV, which has previously been reported as indicative of the formation of a 2DEG due to polarization fields at the interface between GaAs and InGaP 2 [21,22] and corresponds to the region of the sample shown in the inset of Fig. 1(a), close to the rear heterojunction.…”

“…However, it is important to note at this stage that Nextnano3 does not account for any residual CuPt ordering of the InGaP 2 material, which is known to occur in samples grown under similar conditions [17,18]. It has been shown that partial CuPt ordering of the InGaP 2 gives rise to polarization fields and hence sheet charge at the interfaces with the GaAs, which we expect to further exaggerate the band bending observed at the interfaces [20][21][22]. This is important because the triangular potential that arises due to this band bending has been reported to lead to the formation of a two-dimensional electron gas (2DEG) close to the interface [21,22].…”

Electronic Structure of Ordered Ga0.5In0.5P/GaAs Heterointerface Studied by Raman-Scattering and Photoluminescence-Excitation Measurements

“…Actually, by magneto-PL measurement, we confirmed the degenerated Fermi level with the quantized electron state. 7) The accumulated electron densities estimated from the L þ -mode frequency are $1:93 Â 10 18 and $1:46 Â 10 18 cm À3 for the sample with of 0.32 and 0.54, respectively. 22,23) The electron density for the sample with of 0.30 is estimated, from the frequency of the L À mode, to be > 4:0 Â 10 18 cm À3 .…”

“…6,7) The PL spectrum from the GaAs layer shows signals attributable to quantized electron states in a triangular potential and the Fermi-edge singularity. Furthermore, a clear optical Shubnikov-de Haas (SdH) oscillation has been observed in the PL intensity.…”

“…[1][2][3][4][5][6][7] Electron depletion in the GaAs layer was observed at the heterointerface of n-GaAs/n-Ga 0:5 In 0:5 P. 1,2,8) On the other hand, electron accumulation occurs at the lower band-gap-energy side of the heterointerface of Ga 0:5 In 0:5 P/ GaAs. 2,[4][5][6][7]9) Such electronic structures are caused by spontaneous polarization and piezoelectricity in the ordered Ga 0:5 In 0:5 P layer. 3,4) When Ga 0:5 In 0:5 P is polarized by the ordering, a negative (positive) sheet charge appears at the top (bottom) side of the Ga 0:5 In 0:5 P layer.…”