solid-state method impurity formation due to evaporation of chemical from reaction mixture on high temperature
What do you mean by solid state method?
In general during compound thin film deposition/growth, if one of the elements has a much higher vapor pressure than the other (such as S in MoS2, Te in Bi2Te3 etc), then that element has a higher probability of reevaporation from the substrate. Similarly, during more complex CVD growths, different species have different vapor pressures. So depending on the reactor's pressure during growth, higher vapor pressure species will desorb quicker leaving behind vacancies. This leads to defects and unintentional doping in compound semiconductors. When the substrate temperature is very high, it reduces the sticking coefficients of some species, leading to an even higher rate of desorption and defect formation.
The system loses the volatile element. Therefore, there are a phase appears, with a deficit of this element (nearest in the diagram of state, if it is known). To reduce this effect, an excess of the volatile element (or substance) is usually added, the amount of which depends on the synthesis conditions (even reactor shape etc.), i.e. should be chosen experimentally.
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