Direct observation of ordered crystalline organic quantum-well structures using reflection high-energy electron diffraction

We directly observe by reflection high-energy electron diffraction, the quasiepitaxial growth of crystalline organic quantum-well structures grown by the ultrahigh vacuum process of organic molecular beam deposition. We show that each of four alternating layers of two organic molecules grows in a crystalline form without sufficient strain to induce amorphous growth, regardless of significant lattice mismatch which might exist between the alternating films. Our results clearly demonstrate the ability to engineer a completely new class of van der Waals-bonded thin film materials and structures based on crystalline organic semiconductors, with applications to optoelectronics.