Lattice constant
A chemical substance in the solid state may form crystals in which the atoms, molecules, or ions are arranged in space according to one of a small finite number of possible crystal systems (lattice types), each with fairly well defined set of lattice parameters that are characteristic of the substance.These parameters typically depend on the temperature, pressure (or, more generally, the local state of mechanical stress within the crystal),[2] electric and magnetic fields, and its isotopic composition.The lattice parameters of a crystalline substance can be determined using techniques such as X-ray diffraction or with an atomic force microscope.An alternative method is to grade the lattice constant from one value to another by a controlled altering of the alloy ratio during film growth.The rate of change in the alloy must be determined by weighing the penalty of layer strain, and hence defect density, against the cost of the time in the epitaxy tool.
parallelepipedunit cellscrystal latticesimple cubicunit cellSI unitangstromsnanometerpicometresdegreeschemical substancecrystalsmoleculescrystal systemstemperaturepressuremechanical stresselectricmagnetic fieldsisotopiccrystal defectscubic systemdiamondhexagonal systemX-ray diffractionatomic force microscopeepitaxial growthsemiconductor materialsband gaplight-emitting diodesdiode lasersgallium arsenidealuminium gallium arsenidealuminium arsenideindium gallium phosphidewafersCrystal structureDiamond (FCC)graphiteHexagonalWurtziteZrC0.97HfC0.99VC0.97NbC0.99TaC0.99OrthorhombicLiNbO3BaTiO3Tetragonal perovskiteSrTiO3Cubic perovskiteCaTiO3Orthorhombic perovskitePbTiO3EuTiO3Bibcode