Tracing the 5000-year recorded history of inorganic thin films from ∼3000 BC to the early 1900s AD

Abstract

Gold is very likely the first metal discovered by man, more than 11 000 years ago. However, unlike copper (similar to 9000 BC), bronze (similar to 3500 BC), and wrought iron (similar to 2500-3000 BC), gold is too soft for fabrication of tools and weapons. Instead, it was used for decoration, religious artifacts, and commerce. The earliest documented inorganic thin films were gold layers, some less than 3000 angstrom thick, produced chemi-mechanically by Egyptians approximately 5000 years ago. Examples, gilded on statues and artifacts (requiring interfacial adhesion layers), were found in early stone pyramids dating to similar to 2650 BC in Saqqara, Egypt. Spectacular samples of embossed Au sheets date to at least 2600 BC. The Moche Indians of northern Peru developed electroless gold plating (an auto-catalytic reaction) in similar to 100 BC and applied it to intricate Cu masks. The earliest published electroplating experiments were similar to 1800 AD, immediately following the invention of the dc electrochemical battery by Volta. Chemical vapor deposition (CVD) of metal films was reported in 1649, atmospheric arc deposition of oxides (Priestley) in the mid-1760s, and atmospheric plasmas (Siemens) in 1857. Sols were produced in the mid-1850s (Faraday) and sol-gel films synthesized in 1885. Vapor phase film growth including sputter deposition (Grove, 1852), vacuum arc deposition ("deflagration," Faraday, 1857), plasma-enhanced CVD (Barthelot, 1869) and evaporation (Stefan, Hertz, and Knudsen, 1873-1915) all had to wait for the invention of vacuum pumps whose history ranges from similar to 1650 for mechanical pumps, through similar to 1865 for mercury pumps that produce ballistic pressures in small systems. The development of crystallography, beginning with Plato in 360 BC, Kepler in 1611, and leading to Miller indices (1839) for describing orientation and epitaxial relationships in modern thin film technology, was already well advanced by the 1780s (Hauy). The startin