Properties of Topological Semimetal Cd₃As₂ Thin Films as a Function of Growth Optimization and Buffer Choice

The Dirac semimetal Cd₃As₂ is a high mobility, 3D topological semimetal with potential for exploration of quantum phenomena and future information science devices. However, the dependence of its topological properties on growth and heterostructure design is not well explored. Such parameters include growth temperature, dislocation density, and biaxial strain owing to lattice mismatch. The growth of Cd₃As₂ on different abrupt metamorphic buffer layers is therefore completed via molecular beam epitaxy. The aforementioned growth variables are considered for their effect on the final electronic and physical quality and characteristics of the thin film Cd₃As₂.<br/>Cd₃As₂ is grown on relaxed AlInSb, GaInSb, and InAsSb layers with engineered lattice constants at temperatures ranging from 50 to 130 °C. X-ray diffraction and transmission electron microscopy are used to evaluate the buffer layer quality and threading dislocation density. Van der Pauw measurements are conducted to determine carrier mobility and density according to the experimental variables. With the objective of maximizing electron mobility, films are grown over a range of variables including layer thickness and annealing times.