Compensation of grain growth enhancement in doped silicon films

In thin films (1140 Å) of silicon doped with phosphorus, secondary or abnormal grain growth leads to bimodal grain size distributions and eventually to grains much larger than (≳25×) the film thickness. The resulting grains have nonrandom texture and are thought to be the result of surface-energy-driven secondary grain growth. The rate of secondary and normal grain growth increases with increasing P content. This rate increase is thought to be due to an increase in the grain boundary mobility. The rate of normal grain growth is unchanged or slightly increased when films are doped with boron. The secondary grain boundary mobility enhancement that occurs due to P doping can be compensated (reduced or eliminated) when films are co-doped with B.