In TNL-EpiGrow simulator, MBE reactor conditions are achieved by the incidence of one or more molecular beams which are generated in effusion cells, upon a substrate material. An effusion cell consists of a heated crucible containing the source material which sublimates or evaporates to form a molecular beam.
TNL-MBE simulator, various elemental effusion sources can be chosen and each crucible is heated to produce neutral atomic and molecular beams under a refined form of vacuum evaporation. The atomic and molecular beams move forward due to the thermal velocities on a heated substrate under ultra high vacuum (UHV) without any interaction among them. TNL-MBE simulator can be used to optimize the process which has precise control over thickness, alloy composition and intentional impurity (doping) level.
At the substrate surface, the arriving atoms or molecules of the source materials can undergo a number of processes, as summarised. Atoms weakly bound to the surface by van der Waals forces are treated physiosorbed, whereas those bound to the substrate by stronger chemical bonds are treated as chemisorbed. To become incorporated into the lattice, an atom must become chemisorbed at an epitaxial site and form bulk-like bonding configurations. The rate at which this occurs is defined through incorporation rate. Atoms and molecules have flexibilities to migrate across the surface, desorb back into the vacuum, or migrate into the crystal itself. Reactions between adatoms can occur as well, and this can be a crucial stage for breaking up large molecules.
Vapor Pressure of the effusor
cell element is calculated using crucible temperature and atomic number
Vapor pressure in the range of 10-15 to 10-3 atm,
flexibility to study the IV/IV, V/III and VI/II flux ratio and temperature dependences
of the island characteristics,
Adsoption, hopping and desorption rates from kMC algorthims,
accurate prediction of the rate of growth of the film,
The surface morphology and defect density as a function of reactor input conditions,
Descending steps in form of Schwoebel-Ehrlich barrier and ascending steps in form of incorporation barrier,
Nearest neighbour (n-n) interaction contribution,