The technological advancement occurred over last few decades is always related to the advancement in computer and electronic industry. The miniaturisation of electronic devices has been achieved over half a century is explained using G. Mooreâ€™s assumption (Mooreâ€™s law). Industries have adopted a top-down approach to fabricate intricate electronic circuitry which has resulted in the computers which helped us to solve many difficult problems in recent times. But the question is how far (small) we can go in miniaturisation? Is there a limit? In this talk, I will briefly explain the new paradigm in electronics which deals with single molecules. The device structures in the few nanometers need a new way of looking at the conduction mechanism. I will discuss in detail two techniques which are well established to study the conduction via single molecule or atomic wires. I will explain in detail about one of its kind laboratory to fabricate single molecular logic devices on Si(100):H surface. The fabrication and measurements are done in a custom designed ultra-high vacuum system which contains 2-low temperature scanning tunnelling microscopes (LT-STM) and a very high-resolution scanning electron microscope (UHV-NANOPROBE). I will also introduce the new intramolecular circuit laws which are needed to understand the operating mechanism of the devices at single molecule level. At the nanoscale, the leakage current in electronic device is also a major concern for the physicists and Engineers. One of the reasons for a device failure is the leakage current path through the ultrathin gate oxide used in the fabrication of transistor. I will discuss the current understanding of the breakdown of gate oxide at ultra-thin limit. Our study is based on scanning tunnelling microscopy and have deciphered the real cause of the gate oxide breakdown at nanoscale.