Effect of a GaAs buffer layer grown at low substrate temperatures on a high-electron-mobility modulation-doped two-dimensional electron gas

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Abstract
Sidegating in GaAs integrated circuits can be eliminated in molecular beam epitaxially grown structure with the incorporation of a GaAs buffer layer grown at low substrate temperatures (200–300 °C). We have grown two films which were identical except one had the low‐temperature buffer layer included in the film structure. The films were modulation‐doped heterojunctions designed to produce a high‐mobility two‐dimensional electron gas. The electrical characteristics of the two‐dimensional electron gas were identical for the two samples. No deleterious effect on the mobility or carrier density was observed with the incorporation of the low‐temperature buffer layer. At 4.2 K both films exhibited carrier densities of 4×1011 cm−2 and mobilities of (1.4–1.7)×106 cm2/V s in the dark. After a brief illumination at 4.2 K, the samples exhibited carrier densities of 5×1011 cm−2 and mobilities of (1.6–2.0)×106 cm2/V s. These electron mobilities are comparable to the highest electron mobilities ever obtained at these electron densities.

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