Atomically Smooth Defect-Free III-As Heterostructures on InP(111) Substrate for Next-Generation Electronic Devices

Research into Zinc Blende III–V compound semiconductors has focused almost entirely on growth on (001)-oriented substrates for more than five decades. This is because high-quality epitaxial layers can be achieved relatively smoothly when III–Vs are grown on (001) substrates. However, emerging technologies generated renewed interest in the growth of high-quality III–Vs on (111)-oriented substrates. Prime examples of these applications are devices based on spin transport, and low-anisotropy tensile-strained quantum dots for quantum computing applications. Growth on (111) substrates could also help understand the growth of complex chalcogenides. Exploring these applications requires high-quality epitaxial thin films on (111) substrates. Here, we demonstrate for the first time the atomically smooth and defect-free growth of nanoscale InGaAs/InAlAs superlattice on InP(111)-oriented substrate using molecular beam epitaxy (MBE). This was achieved by optimizing the substrate misorientation angle and growth conditions. The growth optimization was guided by scanning transmission electron microscopy Moiré geometrical phase analysis and density functional theory calculations. It is shown that ensuring the step-flow growth mode for each ternary layer is the most effective way of achieving high-quality epitaxial structures on (111)-oriented substrates. This work sets the stage for developing InGaAs/InAlAs/InP(111) electronic and photonic structures with properties that can be tuned with strain-mediated piezoelectric field engineering in high-quality epitaxial thin films. The reported observations should help optimize epitaxy in other Zinc Blende material systems for the structure that could benefit from the tunable piezoelectric effects.