How Do You Judge The Performance Of An R&D Employee

Well Swati,
Research persons are masters in their field and are more deeply into their work. Their work consists of long and long hours, which is purely because of their interest.
Though your ideas are effective, I would again like to mention, you just cant impose any KPI and KRA for research persons. A research itself means based on intellectual investigation and aimed at discovering, interpreting, and revising human knowledge on different aspects of the world. so it is something unpredictable, not defined in a proper sense.
Actually you cant force research persons, I mean they are their masters in their work and dont like to be ordered by some HR / Management person,, because if they start to argue technically on the possibility of your KRA, KPI you would not be able to answer them..

Hi Manasi,
I agree with some suggestion given by Swati & Amit.Finally I will like to give some suggestion .
1 You can definitely evaluate Phd guys but depend upon their position .If someone @ higher level then let higher authority to evaluate them like VP HR,Director of org.
2 For others don't hurt their ego because normally it has been said they are little bit sensitive.
3 Keep your EQ at high level and evaluate always positive will come out.
All the best
regards
prashant