Effects of impurity (N2) on thermo-solutal convection during the physical vapor transport processes of mercurous chloride

Abstract

For Ar=5, Pr=1.18, Le=0.15, Pe=2.89, Cv=1.06, <TEX>$P_B$</TEX>=20 Torr, the effects of impurity <TEX>$(N_2)$</TEX> on thermally and solutally buoyancy-driven convection (<TEX>$Gr_t=3.46{\times}10^4$</TEX> and <TEX>$Gr_s=6.02{\times}10^5$</TEX>, respectively) are theoretically investigated for further understanding and insight into an essence of thermo-solutal convection occurring in the vapor phase during the physical vapor transport. For <TEX>$10K{\leq}{\Delta}T{\leq}50K$</TEX>, the crystal growth rates are intimately related and linearly proportional to a temperature difference between the source and crystal region which is a driving force for thermally buoyancy-driven convection. Moreover, both the dimensionless Peclet number (Pe) and dimensional maximum velocity magnitudes are directly and linearly proportional to <TEX>${\Delta}T$</TEX>. The growth rate is second order-exponentially decayed for <TEX>$2{\leq}Ar{\leq}5$</TEX>. This is related to a finding that the effects of side walls tend to stabilize the thermo-solutal convection in the growth reactor. Finally, the growth rate is found to be first order exponentially decayed for <TEX>$10{\leq}P_B{\leq}200$</TEX> Torr.