hi,

see there is many recruitment comes for scientist or engineer post in isro drdo. from past 5 years isro recruiting b.tech passed candidates for scientist post. but you may know that there is various members now present in isro you are from physics background and also done phd courses. however you can not get scientist post right after completing bsc courses.you may work as an technical assistant post.  I would suggest you to do msc from reputed institute and do phd also.