D. W. Jung

Enhanced Electron–Electron Interactions in GaAs Layers Doped with High Concentrations of Donor and Acceptor Impurities

Magneto-transport properties of Si- and Be-doped GaAs layers grown by molecular-beam epitaxy at low temperatures were studied in order to observe effects of electron–electron interactions enhanced by doping high concentrations of donor and acceptor impurities. The negative magneto-resistance was observed from n-type samples in the whole measured temperature range up to room temperature. Magneto-conductance curves above 150 K are in close accord with calculations based on the localization theory, while those below 150 K at high magnetic fields are explained with the theory of electron–electron interactions. The temperature-dependence of the inelastic scattering time which was derived from the magneto-conductance curves suggests that it is determined by electron–electron collisions at temperatures below 150 K. Results of samples with different impurity concentrations show that doping of higher impurity concentrations along with lower carrier concentrations leads to the significant enhancement of electron–el...

Large anomalous Hall resistance of pair δ-doped GaAs structures grown by molecular-beam epitaxy

Beryllium/silicon pair δ-doped GaAs structures grown by molecular-beam epitaxy exhibit a Hall resistance which has a nonlinear dependence on the applied magnetic field and which is strongly correlated to the negative magnetoresistance observed under the applied magnetic field parallel to the δ-doped layers. Dependence of the occurrence of the nonlinear Hall resistance on the growth condition is investigated. A significantly large increase in both the magnitude and the nonlinearity of the Hall resistance is observed from samples whose GaAs buffer layers are grown under the condition of a low As∕Ga flux ratio. Reflection high energy electron diffraction and electron microscope observations show that a faceted surface develops with the growth and postgrowth annealing of a GaAs buffer layer under the condition of a low As flux. From samples which have only Si δ-doped layers and exhibit the n-type conduction, such nonlinear Hall resistance is not observed. The nonlinearity of the Hall resistance of Be∕Si pair ...

Photoluminescence study on heavily donor and acceptor impurity doped GaAs layers grown by molecular-beam epitaxy

Gallium arsenide layers doped with high concentrations of Be and Si by molecular-beam epitaxy are studied by photoluminescence (PL) spectroscopy. PL peaks from doped layers are observed at energies significantly lower than the band-gap of GaAs. The growth and doping conditions suggest that the origin of these peaks is different from that of low energy PL peaks, which were observed in earlier studies and attributed to impurity-vacancy complexes. The dependence of the peak energy on the temperature and the annealing is found to differ from that of the peaks attributed to impurity-vacancy complexes. On the basis of these observations, it is suggested that the low energy peaks are attributed to short range ordered arrangements of impurity ions. This possibility is examined by calculations of the PL spectra with models of pairs of acceptor and donor delta-doped layers and PL experiments of a superlattice of pairs of Be and Si delta-doped layers.

Direct correlation of negative magnetoresistance with concentrations of localized holes in Be delta-doped GaAs structures

The origin of negative magnetoresistance of GaAs structures with a pair of Be and Si delta-doped layers is investigated with samples in which Be and Si doping concentrations are selectively varied. Magnitudes of negative magnetoresistance are directly correlated to concentrations of localized holes in these samples, suggesting that the negative magnetoresistance results from scattering of carriers by spins associated with these localized holes. The temperature dependence of magnetoresistance curves of the samples which exhibit large negative magnetoresistance is described by the Brillouin function with the Lande g factor and total angular momentum J whose values are expected for a localized hole in GaAs.