Impacts of growth conditions on InAlBiAs electrical properties and morphology

Abstract

As a highly mismatched alloy class, dilute bismuthide materials exhibit strong valence band-Bi impurity state interactions, leading to large bandgap bowing parameters and strong spin–orbit coupling due to the inclusion of Bi in III-V semiconductors. Such properties make the dilute bismuthides ideal candidates for devices requiring band and strain engineering, particularly those in the infrared regions. In this work, the molecular beam epitaxy growth of the dilute bismuthide InxAl1−xBiyAs1−y on InP is studied. To address challenges universally faced in dilute bismuthide growth, a growth–space diagram is constructed to better understand the conditions needed for Bi incorporation and droplet-free growth of the class of dilute bismuthide materials. From this understanding, high-quality, droplet-free growth of In0.52Al0.48BiyAs1−y with up to 5.1% Bi is demonstrated. The n-type unintentional doping of these films is found to be ∼1013–1015 cm−3 with a free carrier mobility of ∼700–1500 cm2/(V s). From these films, the compressive strain induced by Bi incorporation is measured to be (0.190 ± 0.004)% strain/(% Bi) for In0.52Al0.48BiyAs1−y. Using this value to offset strain, lattice-matched InxAl1−xBiyAs1−y on InP is demonstrated.