Transport properties of silicon delta-doped GaAs in high electron density regime

We report results for Si layers embedded in GaAs, extending from the delta-doped (delta-doped) range up to 6 monolayers derived by means of variable temperature resistivity and Hall effect measurements, secondary ion mass spectrometry and high resolution X-ray diffractometry techniques. The conductivity transition from free carrier transport in ordered delta-layers (< 1 ML) to strongly-localized two-dimensional variable range hopping transport under potential fluctuation disordered conditions (> 4 ML) is clearly observed. This observation is in good agreement with the secondary ion mass spectrometry and high resolution X-ray diffractometry data. Results from the intermediate case with 2-3 MLs are also discussed.