There are good opportunities if you have completed your M.S. in Cell Biology from USA and B.Tech Biotechnology from India. You can a get a job in India and there are several companies also but you have to match up your specialization with the company profile. There are several companies in Bangalore, Hyderabad and Ahmadabad belt. You need not require any certification to get into companies. Once you join the company, they will take care of the certification issues if any. I suggest you to go for PhD in parallel to enhance your job opportunities since Biotech Ph.D.s are very less in number comparatively.
Clinical Research after B.Tech. Biotech: ICRI is quite good and authentic in clinical research as there are very less registered courses in India. Before joining the course please check the curriculum, faculty and important one is affiliation of the institute by University. Once you satisfy with the above parameters you can go ahead. Website of ICRI is www.icriindia.com .
B.Tech. Chemical Engineering: Chemical Engineering is a tough but good and important field of study. The major jobs you get are in the plants as a chemical engineer. You are sole person responsible to take care of the reaction rate in a bulk manufacture plant. Huge demand is there for chemical engineering in U.S.A. and Europe. In India also, opportunities are increasing with the growth of bulk manufacturing. Chemical engineering candidates can enter into bioinformatics also which has great application value in Pharmaceutical industries. In India many bioinformatics divisions are being handled by Chemical Engineers.