Is it possible to do PhD after b. tech ? If yes, what is the procedure?
Yes,
Few colleges allow students to pursue M.Tech-PHd dual degree to the B.Tech graduates.
Link of two colleges are given below-
IIT Jodhpur (http://iitj.ac.in/academics/index.php?id=acad_program&&prog=50)
IIT Kharagpur (http://www.iitkgp.ac.in/files/phd_ad.pdf)
You can search for more colleges and also contact them to know about the eligibility conditions as the admission process will vary from one college to another.
Dear Rekha
Yes, you can. IF you can able to qualify the Gate exam after B.Tech then definitely you're eligible to do Ph.d. It needs lot of knowledge and also you need to publish some papers too. So please take care of that.
All the best.