Recent developments in the emerging field of crystalline p-type transparent conducting oxide thin films

Transparent, p-type semiconducting crystalline thin films have recently gained tremendous interest in the field of active devices. All-transparent junctional devices have begun a new generation in the optoelectronics technology called “Invisible Electronics”. Non-stoichiometric and doped versions of various new types of p-type transparent conducting oxides (p-TCO) with improved optical and electrical properties have been synthesized in the last few years in this direction. A wide range of deposition techniques has been adopted to prepare the films. In this review we have tried to discuss the origin of p-type conductivity in these transparent oxides. Also an up-to-date and comprehensive description of different p-type transparent conducting oxide thin films is presented. The growth techniques of these films along with the relative deposition parameters are reviewed in detail. Electrical and optical properties of the films and fabrication of all-transparent diodes are discussed which are important in the development of “Transparent Electronics”. Also, recently, the research on nanostructured materials generates great interest in the scientific community and offers tremendous opportunities in the field of physics, chemistry, materials science and related interdisciplinary areas because of new properties exhibited by them and challenging problems thrown up for providing theoretical concepts in physics associated with it. Here, we have also discussed in brief, the formation of different nanocrystalline p-TCO films, which may open up an extremely important and interesting field of research for the fabrication of all-transparent nanoactive devices and give a new dimension in the field of “Transparent Electronics”.