Study on Effects of Different Carrier Gases on Characteristics of the Supersaturated Environment in the One-/Multi-section Growth Tube

The supersaturation profiles in the one-/multi-section growth tube were predicted under the conditions of different carrier gases for two kinds of typical supersaturation-achieving methods. The results show that Lewis number (Le) of the carrier gas is an important factor affecting the supersaturation profiles. For the one-section growth tube, the carrier gas with a smaller Le is beneficial to a higher level and flatter trend of supersaturation profiles for method 1, where the supersaturated environment is achieved by a cool saturated flow into a warm-walled growth tube. However, for the carrier gas of a larger Le, the higher level but less stable supersaturation profiles are presented from method 2, with a warm saturated flow into a cold-walled growth tube. With the carrier gas of large Le (>1) from method 1 and the carrier gas of small Le (<0.5) from method 2, an efficient supersaturated environment cannot be achieved under the ordinary conditions. In the multi-section growth tube, the more minimum number of the sections is selected for stable supersaturation profiles with the carrier gas of larger Le. Additionally, the sections of a flatter supersaturated environment are closely related to the achieving methods of a supersaturation environment, the whole length of the growth tube, and radial positions.