Germanium Hyperdoping by Pulsed Laser Melting

In later years Germanium gained new interest thanks to its many properties that make it an appealing material in different technological fields, from solar cells, to gamma-ray or gas sensors, even to q-bit technology and, obviously, nanoelectronics. Many of these applications require the ability to fabricate highly doped and high quality Ge layers, to enhance its already good characteristics. In this work, we present a combination of metallic layers deposition and diffusion through Pulsed Laser Melting as an alternative to conventional techniques to obtain the incorporation and activation of alluminium, gallium and antimony as a dopant in crystalline germanium samples. A broad characterization of the obtained material has been conducted to evaluate the morphological, chemical, and electrical properties of the doped samples. The characterizations proved the formation of doped layers with very good and stable surfaces, low resistivities and excellent results in terms of active dopant concentration. This confirms that pulsed laser melting (PLM) is indeed a simple and cheap doping method, with a thermal budget lower than other methods commonly used and, at the same time, able to achieve record activation levels with no residual damage and excellent electrical properties relevant for Ge future advanced devices.