This was my Post Graduate Micro/Nano Fabrication project based on fabrication of Semiconductor Devices using III-Vcompound semiconductor wafer (GaAs) in the Nanotechnology Cleanroom and was likely to achieve the room temperatureeffect known as negative differential resistance of RTD, both under room temperature and liquid Nitrogen Temperature, andfinds application in oscillator circuits. This was then expected to extend to the Fabrication of QCL's as my future project. Fabrication Process: Photo-Lithography, Wet Chemical Etching, Evaporation/Thin film Metallization, Lift-off, Annealing, Packaging, Wire bonding and Testing. Equipments Used: Photo-Resist spinner, Contact Mask Aligner, Optical Microscopes, Alpha-Step Profiler, Thermal Evaporator, Rapid Thermal Annealer and Ball bonder.