If you want to go for M.Tech through Gate then your B.Sc should be of 4 years.
After bsc physics, you have ample opportunities to get ahead in your field.
Master of Science (M.Sc) courses are offered in areas mentioned here-
Physics
Applied Physics and Ballistics
Applied Physics
Bio Physics
Engineering Physics
Geophysics
Marine Geo Physics
Medical Physics
Renewable Energy
Nuclear physics
Vacuum sciences
Other Master level Courses In Physics
M.Sc. (Physics) + Certificate Program in Training & Development
Masters of Science & Technology in Geo Physics
Master of Philosophy (M. Phil) in Applied Physics
Master of Philosophy (M. Phil) in Physics
PhD Courses in Physics