Mixed polytype/polymorph formation and its effects on the electronic properties in InSe films grown by molecular beam epitaxy on GaAs(111)B

• DOI: 10.48550/arxiv.2404.12578
• Publication Date: 2024-04-18
• Authors: Maria Hilse; Justin Rodriguez; Jennifer L. Gray; Jinyuan Yao; S.Q. Ding; Derrick Shao Heng...; Mo Li; Joshua Young; Ying Liu; Roman Engel‐Herbert
• Keywords: Condensed Matter - Materials Science; Materials Science (cond-mat.mtrl-sci); FOS: Physical sciences

The top-down synthesis of inherently ferroelectric semiconductors and their integration with traditional material platforms have the potential to enable new low power logic devices, harness bulk photoelectric effect for more efficient photovoltaic cells. InSe is a layered van der Waals compound exhibiting multiple polytypes, semiconducting gamma-InSe revealing non-centrosymmetric space group showing high carrier mobility at room temperature. Here we report growth films on close lattice matched semi-insulating GaAs(111)B substrates by molecular beam epitaxy (MBE). Excellent nucleation behavior resulted in smooth, single phase films. dominant polytype determined from X-ray diffraction was targeted gamma-InSe, however Raman spectroscopy revealed spatial variations overall low-intensity vibration modes. Transmission electron microscopy uncovered presence three polytypes beta, gamma, epsilon-InSe coexisting arranging nanosized domains. different can be interpreted as sequences stacking faults rotational twin boundaries made individual Se-In-In-Se layers P-6m2 symmetry. A second, centrosymmetric layer polymorph identified P-3m symmetry, which typically not present phases. First principles calculations small formation energy differences between polymorphs yet sizeable electronic properties. Nanoscale domain sizes varying thus disorder grown that dominated transport Our results indicate bottom-up thin film viable route towards stabilization bulk.