hi,

yes it is possible to do mtech +,PhD courses. most of the iits and nits offers mtech students at the end of mtech curriculum to do PhD ..thus it is calls integrated PhD. you may also apply for integrated PhD in jadavpur university on nano technology. though in India doing PhD from iits is highly prestigious. you will be offered to do PhD course after mtech if you have certain marks criteria in btech , mtech and good recommendations from professors of mtech courses. if you are interested to do mtech+PhD you may opt for ms in USA or other foreign countries where ms is a 5 years course includrs  2 years masters course and 3 years PhD course.