The first and foremost requirement is to obtain an extremely pure germanium or silicon. Impurity of less than one part in ten billion (1010) is required for most semiconductor device fabrication to-day. For obtaining pure semiconductor material it is first purified chemically. For reducing the impurities further, and to ensure the formation of a mono crystalline structure, a technique known as flatting zone is quite often employed.The mono crystalline structure is formed through the use of a small seed of semiconductor (e.g., silicon or germanium). The seed itself is a monocrystal that has been very carefully cut along the face of its cubic lattice. Support clamps are employed to hold the low-purity polycrystalline rod.