How to have a Hashrate of 20 TH/s?

[jon-lehi.daduya]

I want to build a bitcoin miner with 20 TH/s. I know the hardware components needed but I don't know exactly is the factor to have a desired hashrate.
I have 0 cost on electricity too.

Does the power of Hash comes from the Memory size of the RAM , Graphics Card or Hard Drive?

Basically what hardware is affected the most to increase hashrate?

Please and Thank you.