Appearance and destruction of spatial correlation of DX charges in GaAs

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Abstract
Measurements of the Hall coefficient and the conductivity in n-GaAs heavily doped with silicon were performed at 4.2 K under hydrostatic pressure applied at an elevated temperature. The procedure ensures that a metastable occupation of the DX centres by electrons is induced. As shown earlier, electric charges on DX centres form, under these conditions, a spatially correlated system of charges. The correlation marks its presence as an enhancement of the electron mobility. Here the authors study the destruction of the spatial correlation of donor charges by illumination with an LED. A calculation within the short-range correlation model accounts well for the decrease of the mobility seen after illumination.