yes, you can apply for DRDO entrance exam after B.Tech. IT course for DRDO Scientist Entry Test .. DRDO is Defence Research and Development Organization conducts Scientist Entry Test every year for recruitments on scientist posts .

required Qualification :
you have to passed with minimum first class degree in engineering with any of following branch :

Electronics & Communication Engineering
Mechanical Engineering
Computer Science & Engineering
Chemical Engineering
Electrical Engineering

Age Relaxation :
- upto 3 years for OBC
- upto 5 years for ST/SC/Handicap

Nationality : Only for Indians

DRDO SET exam syllabus :

Chemical Engineering:

Process Calculations and Thermodynamics
Fluid Mechanics and Mechanical Operations
Heat Transfer
Mass Transfer
Chemical Reaction Engineering
Instrumentation and Process Control
Plant Design and Economics
Chemical Technology

Computer Science and Engineering:
Theory of Computation
Digital Logic
Computer Organization and Architecture
Programming and Data Structures
Algorithms
Compiler Design
Operating System
Databases
Computer Networks

Electronics and Communication Engineering:
Networks
Electronic Devices
Analog Circuits
Digital Circuits
Signals and Systems
Control Systems
Communications
Electromagnetic

Electrical Engineering:

Electric Circuits and Fields
Signals and Systems
Electrical Machines
Power Systems
Control Systems
Electrical and Electronic Measurements
Analog and Digital Electronics
Power Electronics and Drives

Instrumentation Engineering:

Basics of Circuits and Measurement Systems
Transducers, Mechanical Measurement and Industrial Instrumentation
Analog Electronics
Digital Electronics
Signals, Systems and Communications
Electrical and Electronic Measurements
Control Systems and Process Control
Analytical, Optical and Biomedical Instrumentation

Mechanical Engineering:
Engineering Mechanics
Strength of Materials
Theory of Machines
Vibrations
Design
Fluid Mechanics
Heat-Transfer
Thermodynamics
Applications
Engineering Materials
Metal Casting
Forming
Joining
Machining and Machine Tool Operations
Metrology and Inspection
Computer Integrated Manufacturing
Production Planning and Control
Inventory Control
Operations Research