Electrical characteristics of Mg-doped GaAs epitaxial layers grown by molecular beam epitaxy

Abstract

The electrical characteristics of magnesium (Mg)-doped GaAs epitaxial layers grown with different substrate temperatures have been investigated by Hall effect and capacitance–voltage (C–V) measurements at room temperature. The carrier concentration obtained by Hall measurements was decreased from 1.4×1019 to 3.4×1016 cm−3 when increasing the substrate temperature in the range 460–540 °C, and thus the maximum attainable doping density was NA–ND=1.4×1019 cm−3. The depth profiles of doping density, obtained by C–V measurements, show that carriers largely out-diffused toward the surface. This could be attributed to the surface segregation effect, which was predominant in the samples with a high doping density than those with a low doping density. Mg-doped GaAs layers have higher mobility than Be-doped GaAs layers around NA–ND=1018 cm−3. Thus, it is expected that Mg could be effectively used as p-type dopants for highly doped nanostructured semiconductors.