Scanning Tunneling Microscopy - from Birth to Adolescence

We present here the historic development of Scanning Tunneling Microscopy; the physical and technical aspects have already been covered in a few recent reviews and two conference proceedings [l] and many others are expected to follow in the near future. A technical summary is given by the sequence of figures which stands alone. Our narrative is by no means a recommendation of how research should be done, it simply reflects what we thought, how we acted and what we felt. However, it would certainly be gratifying if it encouraged a more relaxed attitude towards doing science. Perhaps we were fortunate in having common training in superconductivity, a field which radiates beauty and elegance. For scanning tunneling microscopy, we brought along some experience in tunneling [2] and angstroms [3], but none in microscopy or surface science. This probably gave us the courage and light-heartedness to start something which should " not have worked in principle " as we were so often told. " After having worked a couple of years in the area of phase transitions and critical phenomena, and many, many years with magnetic fields, I was ready for a change. Tunneling, in one form or another had intrigued me for quite some time. Years back, I had become interested in an idea of John Slonczewski to read magnetic bubbles with tunneling; on another occasion, I had been involved for a short time with tunneling between very small metallic grains in bistable resistors, and later I watched my colleagues struggle with tolerance problems in the fabrication of Josephson junctions. So the local study of growth and electrical properties of thin insulating layers appeared to me an interesting problem, and I was given the opportunity to hire a new research staff member, Gerd Binnig, who found it interesting, too, and accepted the offer. Incidentally, Gerd and I would have missed each other, had it not been for K. Alex Müller, then head of Physics, who made the first contacts [l]. " The original idea then was not to build a microscope but rather to perform spectroscopy locally on an area less than 100 Å in diameter. " On a house-hunting expedition, three months before my actual start at IBM, Heini Rohrer discussed with me in more detail his thoughts on inhomo-geneities on surfaces, especially those of thin oxide layers grown on metal