Room-temperature conductivity and the band structure of n-Ga1−xAlxAs

Abstract
Conductivity measurements on epitaxially grown silicon‐doped n‐Ga1−xAlxAs as a function of Al concentration x, for 0.10⩽x⩽0.65 are presented. Simple two‐probe measurements were made possible by the development of a low‐resistance Ohmic contact, with the contact resistance independent of x. A calculated three band (Γ, X, and L) conductivity of Ga1−xAlxAs as a function of x shows good agreement with the experimental results. The transition from a direct band‐gap semiconductor to an indirect one occurs at xc =0.45 at 300 °K. The device performance, however, begins to be affected at much lower Al concentration.