How old are these Brahmas? This is important. If they're still very young, then the problem is in how you are picking them up.
Chicks are deathly afraid of being picked up from above. It awakens predator fears in their little brains. They react to hands being thrust at them from above their heads as if a hawk was swooping down to kill them. Thus the running away screeching.
If people would forego the typical brooder on the floor with a top access, and instead place a brooder up on a table and access the chicks from an opening built into the side of the box, the chicks will be guaranteed calm and tame and sweet from the very start.
If your Brahmas are older, the process of taming them is similar. Approach them slowly and calmly by getting down on their level and reaching for them very slowly from the side. All chickens react with fear when you swoop down on them from above their heads. After a period of time, the Brahmas will learn you are no threat, and will calm down and be true to their breed, being lovable and cuddly.
Yes, by all means, use treats to grease the skids.