Study on epsilon crossover wavelength tuning of heavily doped germanium-on-silicon in mid-infrared range
Abstract:
In this paper, we demonstrate that n-type heavily doped germanium (Ge) can serve as a sort of CMOS-compatible, permittivity crossover wavelength (at which the real part of permittivity changes sign) wide range adjustable epsilon-zero material in mid-infrared (MIR). The antimony (Sb) doped Ge films with high doping concentrations have been highly crystalline grown on silicon substrates with the molecular beam epitaxy (MBE) process. Our results reveal that the crossover wavelength of doped germanium is highly tunable by adjusting the carrier concentration and crystallinity of the films simultaneously. By optimizing dopant flux and substrate temperature, the maximum carrier concentration can be achieved as high as 1.6×1020 cm-3, resulting in a very short crossover wavelength of 4.31 µm, which is very difficult to realize in group IV semiconductors. The heavily doping process also enables it possible to observe the room temperature photoluminescence (PL) from direct band transition of germanium films.
Related Concept Videos
IR Absorption Frequency: Hybridization
Among the sp, sp2, and sp3 hybridized orbitals, sp orbitals have the maximum s character (50%). Consequently, the electrons are held more closely to the nucleus, resulting in stronger and shorter C–H bonds that...
Biasing of Metal-Semiconductor Junctions
In Schottky junctions, where the semiconductor is n-type, applying a positive voltage to the metal relative to the semiconductor reduces its Fermi...
IR Frequency Region: X–H Stretching
IR Frequency Region: Fingerprint Region
IR Absorption Frequency: Delocalization
In IR...
Interaction of EM Radiation with Matter: Spectroscopy


