You can apply for any institute offering PhD. Specially IITs consider B.Techs for PhD if they have valid GATE score.

If possible take either GATE or NET exam for admission as well as scholarship.

Here are few good places to do phd in India.

Few Good Places To Do PhD In India

Yes, completing a Ph.D. without a master’s degree is possible in some cases. This often depends on your academic background, your research proposal, and the specific requirements of the university or program you are applying to. Do not forget to familiarize yourself with the special rules of the desired institution. https://dissertationwritinghelp.uk/research-proposal-writing-service/

Some universities may offer PhD admission to students without a Master’s degree if they have sufficient research or professional experience relevant to the proposed PhD research. Following are the universities that you can contact;
1. University of Cambridge
2. University of Oxford
3. Imperial College London
4. University College London (UCL)
5. University of Edinburgh

It is necessary to contact the university admission department for the availability of admission to your concerned subject/program. Meanwhile, you can also visit https://www.affordable-dissertation.co.uk/ if you need help with your PhD dissertation research.