If you want to go for M.Tech through Gate then your B.Sc should be of 4 years. So if you fulfill this criteria then you can opt for Gate exam. To know the complete eligibility of Gate 2018 you can go through the below link -

Gate 2018 eligibility

Apart from this, you can go for below provided courses as well -

B.Ed

B.Tech Electronics

M. Sc Acoustics

M. Sc Applied Electronics

M. Sc Astronomy

M. Sc Astrophysics

M. Sc Electronics

M. Sc Geophysics

M. Sc Medical Physics

M. Sc Nuclear physics

M. Sc Physics

M. Sc Physics

M. Sc Vacuum Sciences

Master in Atomic and Molecular Physics
Masters Degree Physics

MBA

MCA

PG Diploma in Physics

Postgraduate Certificate and Diplomas Physics

Postgraduate Certificate in Education Physics

Note : As there are many courses available so better to choose the one in which you have maximum interest and in which you can give your best.

Hope this helps!!!