Al$_x$Ga$_{1-x}$As/GaAs(100) hetermostructures with anomalously high carrier mobility

Structural and spectroscopic methods are used to study the epitaxial layers of n-type Al$_x$Ga$_{1-x}$As solid solutions produced by the metal-organic chemical vapor deposition method. It is shown that, when Al$_x$Ga$_{1-x}$As solid solutions are doped with carbon to a level of (1.2 – 6.7) $\times$ 10$^{17}$ cm$^{-3}$, the electron mobility is anomalously high for the given impurity concentration and twice exceeds the calculated value. It is assumed that the ordered arrangement of carbon in the metal sublattice of the solid solution leads to a change in the average distance between impurity ions, i.e., to an increase in the mean free path of the carriers and, consequently, in the carrier mobility. The observed effect has immediate practical importance in the search for various technological ways of increasing the operating speed of functional elements of modern optoelectronic devices. The effect of the anomalously high carrier mobility in the epitaxial layer of a heteropair opens up new opportunities for the development of new structures on the basis of Al$_x$Ga$_{1-x}$As compounds.