![]() ![]() ![]() These techniques are used widely in semiconductor technology. Studies can be classified as ion implantation, solid-phase doping, monolayer doping, and other methods such as sputtering and chemical solution mixing. īoron doping has grabbed attention for several decades. Boron is one of the essential dopants for shallow doping in silicon because of its good diffusivity. At low energy, the penetrated navigation of ions was mainly directed along crystalline channels rather than moving randomly into semiconductors. It required low-energy ions for implantation by considering thermal redistribution. Shallow doping could create doped layers with depths ranging about dozens of nanometers. The precise control of dimension and dopant concentration of source/drain region to achieve a high shallow doping efficiency is crucial for junction fabrication. The formation of shallow and low resistivity junctions is required for contact resistance reduction and leakage current consideration. The unstoppable development of electronic technology demands the detailed design and effective performance of microelectronics. Schematic of (a) boron-doped silicon, (b) an ion implanter, and (c) ion penetration path into a silicon substrate. This appears like the moving of the positive carrier. Thus, in a boron-doped semiconductor, the holes constantly move around inside the crystal as electrons continuously try to fill them. But when an electron moves into a hole, the electron leaves a new hole in the previous position. In the p-type semiconductors, the holes, like the positive charge, attract electrons. This hole acts like a positive charge, so boron-doped (B-doped) semiconductors are referred to as p-type semiconductors ( Figure 1a). Still, since boron only has three free electrons to provide, a hole is created. During the boron incorporation process into the silicon crystal, the one atom of boron can bond with four silicon atoms. Boron is a p-type dopant with only three electrons in its valence shell. Moreover, group V elements, including phosphorus (P), arsenic (As), antimony (Sb), bismuth (Bi), and lithium (Li), are donors to contribute free electrons in n-type semiconductors. The dopants belonging to group III, such as boron (B), aluminum (Al), gallium (Ga), and indium (In), are referred to as acceptors for p-type semiconductors. In the doping process, a dopant is added, which could play a role as either a donor to contribute an electron or an acceptor to create a hole with the semiconductor crystal that respectively generates two types of semiconductors: n-type and p-type. The intrinsic semiconductors are pure semiconductors without impurities (typical semiconductors of group IV in the periodic table: Si and Ge), in which the number of excited electrons equals the number of holes. In semiconductor technology, doping is a process that introduces delicately controlled amounts of impurities (called dopants) into an intrinsic semiconductor to modify its electrical, optical, and structural properties significantly. ![]()
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