On the hall mobility lowering in GaAs epitaxial layers

Abstract

Early investigations have shown that the electron mobility in GaAs epitaxial layers had always a lower value than estimated theoretically for the same concentration values. Since this fact was established independently of the method of obtaining epitaxial layers, it was assumed that the mobility lowering is a genuine property of the epitaxial layers. In this work several reasons are demonstrated experimentally causing a virtual lowering of the mobility. Incorrect thickness determination and, consequently, incorrect concentration values have been found as the main reason of the lowered mobility evaluations. Methods are proposed for the more correct evaluation of the mobility versus concentration dependences. A great amount of experimental data having been corrected by the suggested method, represents a good correlation between the experimental and calculated mobilities in a wide concentration range. It demonstrates that there is no reason to accept a supposition on the lowered mobility in GaAs (and other) epitaxial layers as a genuine property.