Doping characteristics and electrical properties of Be-doped <i>p</i>-type Al<i>x</i>Ga1−<i>x</i>As by liquid phase epitaxy

Abstract

The liquid phase epitaxial technique has been used to grow Be-doped AlxGa1−xAs in the Al composition range 0&amp;lt;x?0.9, and the doping characteristics and electrical properties of the epilayers have been studied by Hall measurements in the temperature range between 77 and 320 K. The distribution coefficient for Be at 800 °C is about 10 for x&amp;lt;0.4 and decreases to about 1 for x=0.8. High hole concentrations of more than 1018 cm−3 have been easily obtained even in epilayers with an x value as high as 0.9. The acceptor activation energies of the epilayers have been between 10 and 100 meV depending strongly on the x value and NA. The hole Hall mobilities at 300 K are less than 102 cm2/V sec, regardless of Al composition. The variation of the hole mobility with x for the same NA shows that the mobility is controlled by the alloy scattering mechanism. The results obtained in this work suggest that Be can be a useful acceptor in AlxGa1−xAs especially for high x values.