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

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.