High magnetic field transport and photoluminescence in doped InGaAs/InP superlattices

Abstract

Lattice-matched InP InxGa1,xAs short period superlattices x = 0 :53 -doped with Si in the middle of the InP barriers were studied. The samples had a high carrier concentration which lled two minibands. In addition to a peak associated with the electrons from the second miniband, E2, the Shubnikov-de Haas spectra showe d a w ell resolved doublet structure that is assigned to E1 electrons of superlattice wave v ectors kz = 0 and kz = =d. F rom the lineshape of the Shubnikov-de Haas oscillations, an E1 quantum mobility of 970 cm 2 Vs was deduced, which represents an increase of about 40 over the value for periodically delta-doped semiconductors. The photoluminescence exhibits a band at photon energies higher than the InGaAs bandgap and whose FWHM approximates the Fermi energy of the con ned carriers. Thus the photoluminescence observed is consistent with the recombination of electrons con ned by the superlattice potential and photoexcited holes. I IntroductionIn doped superlattices electrons are con ned by a p eriodic potential in one dimension which splits the continuous conduction band into a set of discrete energy minibands. By changing the thickness of the component l a yers and the doping density, the energy spectrum of carriers can be tuned within a wide range. This characteristic makes doped superlattices a unique system in which to study the physical properties of an electronic system with a dimension between 2 and 3, whereby such interesting e ects as negative di erential resistance 1 and chaotic transport 2, 3 can be observed.In addition to the lineshape of the periodic potential and the density of con ned carriers, the lifetime of the single-particle states is also a key factor in determining the electronic properties of the superlattice. Our previous work on periodically delta-doped superlattices 4, 5 has shown that the lifetime of the electronic state at the Fermi energy increases with the average distance between the electron spatial distribution and the ionised impurity sheet. In this work we attempted to reduce the rate of scattering by increasing the distance between electrons and impurities. Results obtained on doped InP InGaAs superlattices are presented. The doping sheet of Si atoms was placed in the InP barriers. In such a structure electrons are repelled by the InP barriers, and this repulsion favours their spatial separation from the impurity atoms, which leads to longer single-particle lifetimes.

Evidence of the miniband formation in InGaAs/InP superlattices

“…However, to the best of our knowledge until now an evidence of the formation of the superlattice bandstructure in the InGaAs/InP SLs was only recently obtained by high-field magnetotransport in Ref. [2]. The photoluminescence data presented in this reference also indicated the existence of the minibands.…”

Miniband effect on optical vibrations in short-periodInxGa1−xAs∕InP

“…However, to the best of our knowledge evidence of the formation of the superlattice band structure in In x Ga 1−x As/ InP SLs has been obtained only recently by high-field magnetotransport measurements. 2 The photoluminescence data presented in Ref. 2 also indicated the existence of the minibands which result from the SL periodicity.…”